WO2025040897A1

WO2025040897A1 - Feed spacer for a spiral wound membrane

Info

Publication number: WO2025040897A1
Application number: PCT/GB2024/052182
Authority: WO
Inventors: Omkar Shrikant Joshi; Tristan Lewis PHILLIPS; Kangsheng BRETHERTON-LIU
Original assignee: Evove Ltd
Current assignee: Evove Ltd
Priority date: 2023-08-21
Filing date: 2024-08-20
Publication date: 2025-02-27
Anticipated expiration: 2026-02-21
Also published as: GB202312767D0

Abstract

There is described a feed spacer for a spiral wound membrane, and a method of preparing a feed spacer. In the method of preparing a feed spacer, the feed spacer is produced by additive manufacturing. The feed spacer comprises a spacer member and a flow modifier member. The spacer member is operable to space apart adjacent components of the spiral wound membrane to form a fluid flow channel. The flow modifier member is operable to direct fluid flow toward a membrane component of the spiral wound membrane in the fluid flow channel. The spacer member is operable to space the membrane component from the flow modifier member so as to form a fluid flow channel above and below the flow modifier member. Also described is a spiral wound membrane comprising the feed spacer; and a water treatment module comprising the feed spacer or spiral wound membrane.

Description

FEED SPACER FOR A SPIRAL WOUND MEMBRANE

FIELD

[01] The present invention relates to a feed flow spacer for a spiral wound membrane, such as a spiral wound membrane for water treatment.

BACKGROUND

[02] Conventional methods of water treatment such as chemical disinfection, solar disinfection, boiling, sedimentation and distillation are not sufficient to meet the portable water requirement of the world’s population at low cost. In order to tackle the problem, more advanced technologies have been established and industrialised, such as pressure driven membrane-based water treatment technologies which in general include ultrafiltration (UF), microfiltration (MF), nanofiltration (NF), and reverse osmosis (RO). By providing the advantages of circumventing the application of thermal inputs, chemical additives and reducing medium regeneration, these methods have significantly improved the water treatment industry.

[03] Membrane filtration is favoured over other water treatment technologies due to, in principle, no significant thermal input, fewer chemical additives and a lower requirement for the regeneration of spent media. Pressure-driven membrane processes are the most widely applied membrane technologies in water treatment, for the removal of particulates, ions, microorganisms, bacteria and natural organic materials, covering different applications from waste treatment from the food and oil industry to seawater desalination.

[04] Spiral wound membranes are a common type of membrane filtration technology that comprise a plurality of membrane envelopes and feed spacers, all wrapped around a central permeate collection tube. The membrane envelope typically comprises two opposed filtration membrane layers (such as comprising an active layer, support layer and backing layer) and a feed spacer. The membrane envelope is typically sealed together along three outer edges and is attached to the central permeate collection tube along a fourth edge.

[05] Feed spacers are an important component used in spiral wound membrane filtration with the main function of providing a flow channel for the feed flow.

[06] Typically, the feed is supplied to the filtration membrane layer through the flow channel created by the feed spacer to separate a mixture of components, generally with the application of a driving force applied across the surface of the membrane, such as transmembrane pressure (TMP), to obtain the filtered permeate in the feed spacer. The permeate is then collected in the central permeate collection tube and the retentate flows out from the flow channel formed by the feed spacer.

[07] Currently, the commercially available feed spacers perform well in many applications; however, the drive to produce new water resources and protect existing water resources demands more advanced feed spacers. New materials and new processing technologies having properties to fulfil the demands are desired.

[08] In general, a robust water filtration module for water treatment should display properties including high chemical, mechanical and thermal stability, good fouling resistance with cleanability, long life span, high permeability and controllable selectivity. Feed spacers for use in these water filtration modules should have commercial accessibility, such as low material and manufacturing costs, high manufacturing scalability, and reasonable lead times to commercialisation.

[09] Therefore, there is a requirement for improved feed spacers for efficient water treatment. It is therefore an object of aspects of the present invention to address one or a few of the problems mentioned above or other problems.

SUMMARY

[10] According to a first aspect of the present invention, there is provided a feed spacer for a spiral wound membrane, such as for water filtration, comprising: a. a spacer member operable to space apart adjacent components of the spiral wound membrane to form a fluid flow channel; and b. a flow modifier member operable to direct fluid flow toward a membrane component of the spiral wound membrane in the fluid flow channel, wherein the spacer member is operable to space the membrane component from the flow modifier member so as to form a fluid flow channel above and below the flow modifier member.

[11] According to a second aspect of the present invention, there is provided a feed spacer for a spiral wound membrane, suitably a feed spacer according to the first aspect of the present invention, wherein the feed spacer is prepared by a method comprising the steps of: a. producing a feed spacer component, optionally comprising a support material, by additive manufacturing; b. removing the optional support material by dissolving the support material with a solvent, or by mechanically removing the support material; c. optionally UV-curing the feed spacer component.

[12] Advantageously, the feed spacer of the present invention may provide high chemical, mechanical and/or thermal stability, good fouling resistance with cleanability, long life span, high permeability and/or controllable selectivity. The feed spacer may promote a higher flux of permeate across a membrane, whilst also reducing the fouling on the membrane surface, reducing the likelihood of increased pressure drop and potential telescoping of the membrane. Advantageously, this also reduces the extent of increase in operating pressure required in applications where constant flux is desired. This may reduce the frequency of cleaning the membrane. Advantageously, the present invention may improve the rejection of at least divalent ions, to improve the selectivity between divalent and monovalent ions. The enhanced permeate flux provided by the feed spacer of the present invention may increase the recovery and permeate yield and may facilitate operating the membrane modules at lower flow rates producing same flux (and hence permeate yield) which may reduce the specific energy consumption.

[13] The feed spacer may have any suitable thickness. The thickness of the feed spacer may be from > 0.25 mm to < 2.2 mm, or > 0.6 mm to < 1 .8 mm, or > 0.8 mm to < 1 .2 mm. The skilled person will appreciate that the thickness of the feed spacer may be adapted depending on the intended application of the spiral wound membrane. For example, reverse osmosis or nanofiltration may be compatible with a thinner feed spacer, whereas spiral wound membranes used for ultrafiltration and microfiltration may require a thicker feed spacer.

[14] The spiral wound membrane may comprise a first and a second membrane envelope, wherein a first side of a feed spacer according to the present invention is operable to be arranged adjacent to, and suitably abut, the first membrane envelope, and a second side of the feed spacer, suitably opposed to the first side, is operable to be arranged adjacent to, suitably abut, the second membrane envelope such as to form a fluid flow channel between the membrane envelops. A spiral wound membrane may comprise a plurality of such arrangements using a plurality of feed spacers according to the present invention.

[15] The feed spacer for a spiral wound membrane may comprise a first side operable to be arranged proximal to, and may extend substantially parallel to, a permeate collection tube, and a second side operable to be arranged distal to, and may extend substantially parallel to, the permeate collection tube. The feed spacer for a spiral wound membrane may comprise a first end operable to be arranged proximal to a feed flow inlet and may extend substantially transverse to the permeate collection tube, and a second end operable to be arranged distal to the feed flow inlet/proximal to the retentate flow outlet and may extend substantially transverse to the permeate collection tube.

[16] In use, there may be fluid connection between a feed flow inlet of the spiral wound membrane and retentate outlet of the spiral wound membrane through the fluid flow channel between adjacent membrane envelopes formed by the feed spacer of the present invention so that feed fluid may be operable to pass from the feed flow inlet to the retentate outlet, with removal the desired permeate through the membrane components of the spiral wound membrane during passage.

[17] The fluid that is operable to flow through the fluid flow channel formed by the feed spacer may be a liquid. For example, the liquid may water, seawater, or the like. [18] The feed spacer comprises a spacer member. The spacer member is operable to provide separation between adjacent components of the spiral wound membrane. This may improve the efficiency of the spiral wound membrane by providing a large surface area to volume ratio.

[19] The adjacent components of the spiral wound membrane may be membrane components. The membrane components may be operable to permit the transfer of permeate(s) across a portion of the membrane components.

[20] The separation provided between the adjacent components of the spiral wound membrane provides a fluid flow channel therebetween. The fluid flow channel may provide spacing through which a fluid may flow from a feed inflow inlet to a retentate outlet of the spiral wound membrane.

[21] Advantageously, the arrangement provided by the feed spacer of the present invention may be operable to improve the efficiency of the spiral wound membrane by presenting a larger surface area of the adjacent components of the spiral wound membrane to be used for the passage of permeate. This arrangement may prevent adjacent components of the spiral wound membrane from contacting or becoming stuck together.

[22] The spacer member may be operable to increase the turbulence and/or tortuosity of the fluid flow passing through the fluid flow channel. The spacer member may be operable to increase the mixing of the fluid flow that passes through the fluid flow channel.

[23] Advantageously, the spacer member may be operable to improve the flux of the spiral wound membrane. The spacer member may be operable to reduce the pressure drop across the feed spacer, thereby reducing the likelihood of damage to the spiral wound membrane from occurring.

[24] The spacer member may comprise a leading face. The leading face may be operable to face substantially upstream into the direction of fluid flow. The leading face may be operable to be the first face of the spacer member that contacts the fluid flow.

[25] The spacer member may comprise a trailing face. The trailing face may be operable to face substantially downstream to the direction of fluid flow. The trailing face may be operable to be the last surface of the face member that contacts the fluid flow.

[26] The leading face of the spacer member may be curved, such as substantially horizontally curved. The curved leading face of the spacer member may be curved away from the incoming fluid flow. The curved leading face of the spacer member may be curved in a downstream direction. Such a curved leading face may be considered to be convex with respect to the direction of the fluid flow.

[27] The leading face of the spacer member may be substantially vertically straight.

[28] The curved leading face of the spacer member may be substantially formed of an arc. The radius of curvature of the curved leading face may be operable to be substantially aligned parallel with the direction of fluid flow. As used herein, ‘substantially aligned parallel’ with respect to the radius of curvature of the curved leading face may be < 20°, such as < 10°, or < 5° from parallel with the direction of fluid flow.

[29] Advantageously, this arrangement may be operable to provide the spacer member with a streamlined leading face. This may reduce the pressure drop of the fluid flow across the feed spacer and the likelihood of the spiral wound membrane becoming damaged due to fluid flow pressure drop.

[30] The trailing face of the spacer member may be curved, such as substantially horizontally curved or substantially planar, such as substantially horizontally planar. The curved leading face of the spacer member may be curved toward the incoming fluid flow. The curved trailing face of the spacer member may be curved in an upstream direction. Such a curved leading face may be considered to be concave with respect to the direction of the fluid flow.

[31] The trailing face of the spacer member may be substantially vertically straight.

[32] The curved trailing face of the spacer member may be substantially formed of an arc. The radius of curvature of the curved trailing face may be substantially aligned parallel with the direction of fluid flow. As used herein, ‘substantially aligned parallel’ with respect to the radius of curvature of the curved trailing face may be < 20°, such as < 10°, or < 5° from parallel with the direction of fluid flow.

[33] Advantageously, this may provide a spacer member with a streamlined profile. This arrangement may reduce the likelihood of flow separation from occurring downstream of the spacer member. This may reduce the fluid flow pressure drop across the feed spacer and the likelihood of the spiral wound membrane becoming damaged due to fluid flow pressure drop.

[34] The radius of curvature of the curved leading face of the spacer member may be from at least 0.04 mm, at least 0.1 mm, at least 0.14 mm.

[35] The radius of curvature of the leading face of the spacer member may be up to 0.3 mm, up to 0.25 mm, up to 0.17 mm.

[36] The radius of curvature of the curved leading face of the spacer member may be from > 0.04 mm to < 0.3 mm, or > 0.1 mm to < 0.25 mm, or > 0.14 mm to < 0.17 mm.

[37] The radius of curvature of the curved trailing face of the space remember may be from at least 0.04 mm, at least 0.1 mm, at least 0.14 mm.

[38] The radius of curvature of the curved trailing face of the space remember may be up to 0.3 mm, up to 0.25 mm, up to 0.17 mm.

[39] The radius of curvature of the curved trailing face of the spacer member may be from > 0.04 mm to < 0.3 mm, or > 0.1 mm to < 0.25 mm, or > 0.14 mm to < 0.17 mm. [40] The spacer member may comprise first and second side faces. The first and second side faces may be substantially opposed.

[41] The first and/or second side face may be curved laterally outwardly from a horizontal crosssection midpoint of the spacer member. In other words, the first and/or second side face may be curved in a direction that is substantially perpendicular to the curvature of the front and trailing faces. The first and/or second side faces may be operable to be outwardly curved in a direction that is substantially horizontally perpendicular to the direction of the fluid flow.

[42] The spacer member may comprise a closed planar curve horizontal cross-section, such as a substantially oval-shaped cross-section.

[43] Advantageously, this arrangement may provide the spacer member with a streamlined profile around which the fluid may flow. This may reduce pressure drop of the fluid flow passing across the feed spacer.

[44] The closed planar curve horizontal cross-section of the spacer member may be substantially formed by an intersection of two arcs. The arcs may curve in an outwardly lateral direction relative to a horizontal cross-section midpoint of the spacer member. The arcs may comprise substantially the same radii of curvature.

[45] Advantageously, this arrangement may reduce the likelihood of flow separation from occurring downstream of the spacer member.

[46] The curved leading face may have a radius of curvature that is smaller than the radius of curvature of the first and/or second side face. The curved trailing face may have a radius of curvature that is smaller than the radii of curvature of the first and/or second side face.

[47] The front and trailing faces may have substantially the same radii of curvature.

[48] Advantageously, this arrangement may provide the spacer member with streamlined profile capable of reducing the hydraulic resistance and the pressure drop of the fluid flow across the feed spacer.

[49] The radius of curvature of the first side face of the spacer member may be from at least 0.4 mm, at least 1 .5 mm, at least > 2 mm.

[50] The radius of curvature of the first side face of the spacer member may be up to 6 mm, up to 3 mm, up to < 2.4 mm.

[51 ] The radius of curvature of the first side face of the spacer member may be from > 0.4 mm to < 6 mm, or > 1 .5 mm to < 3 mm, or > 2 mm to < 2.4 mm.

[52] The radius of curvature of the second side face of the spacer member may be from at least 0.4 mm, at least 1 .5 mm, at least 2 mm. [53] The radius of curvature of the second side face of the spacer member may be from up to 6 mm, up to 3 mm, up to 2.4 mm.

[54] The radius of curvature of the second side face of the spacer member may be from > 0.4 mm to < 6 mm, or > 1 .5 mm to < 3 mm, or > 2 mm to < 2.4 mm.

[55] The spacer member may comprise a lateral axis along the largest width of the spacer member, wherein the spacer member may be substantially symmetrical about the lateral axis. The lateral axis may extend between an apex of each of the opposed curved side faces.

[56] The spacer member may further comprise a longitudinal axis along the largest length of the spacer member. The spacer member may be substantially symmetrical about the longitudinal axis. The longitudinal axis of the spacer member may extend between an apex of the curved leading face and an apex of the curved trailing face.

[57] The longitudinal axis of the spacer member may be operable to be substantially aligned parallel with the direction of the fluid flow.

[58] As used herein, ‘substantially aligned parallel with the direction of the fluid flow’ with respect to the longitudinal axis of the spacer member may mean aligned from at least 10°, at least 25°, at least 30° from parallel with the direction of fluid flow.

[59] As used herein, ‘substantially aligned parallel with the direction of the fluid flow’ with respect to the longitudinal axis of the spacer member may mean aligned up to 65°, up to 50°, up to 40° from parallel with the direction of fluid flow.

[60] As used herein, ‘substantially aligned parallel with the direction of the fluid flow’ with respect to the longitudinal axis of the spacer member may mean aligned from > 10° to < 65°, or > 25° to < 50°, or > 30° to < 40° from parallel with the direction of fluid flow.

[61] Advantageously, parallel alignment of the longitudinal axis of the spacer member with the direction of fluid flow may reduce the hydraulic resistance associated with the spacer member. This arrangement may further reduce the pressure drop of the fluid flow passing across the feed spacer.

[62] The leading face of the spacer member may comprise a width that is smaller than the largest width of the spacer member.

[63] The trailing face of the spacer member may comprise a width that is smallerthan the largest width of the spacer member.

[64] Advantageously, this arrangement may promote a streamlined interaction with the fluid flow, thereby reducing the pressure drop of the fluid flow passing across the feed spacer.

[65] The spacer member may comprise a trailing face that is substantially planar. [66] The trailing face may be wider than the leading face of the spacer member. The width of the planar trailing face may be larger than the width of the leading face of the spacer member. The trailing face may comprise the largest width of the spacer member.

[67] The spacer member may have a substantially wedge-shaped horizontal cross-section. In this configuration, the opposed side walls of the spacer member may be tapered in width between the leading face and the trailing face. The spacer member may be substantially wedge-shaped.

[68] Advantageously, this arrangement may be operable to increase the tortuosity and/or turbulence of the fluid flow, thereby increasing the efficiency of permeate transfer across the adjacent components of the spiral wound membrane.

[69] The largest width of the spacer member may be from at least 0.4 mm, at least 0.6 mm, at least 0.7 mm.

[70] The largest width of the spacer member may be up to 2 mm, up to 1.5 mm, up to 1 mm.

[71] The largest width of the spacer member may be from > 0.4 mm to < 2 mm, or > 0.6 mm to < 1 .5 mm, or > 0.7 mm to < 1 mm.

[72] The width of the leading face may be from at least 0.07 mm, at least 0.18 mm, at least 0.25 mm.

[73] The width of the leading face may be up to 0.53 mm, up to 0.45 mm, up to 0.35 mm.

[74] The width of the leading face may be from > 0.07 mm to < 0.53 mm, or > 0.18 mm to < 0.45 mm, or > 0.25 mm to < 0.35 mm.

[75] The width of the trailing face may be from at least 0.07 mm, at least 0.18 mm, at least 0.25 mm.

[76] The width of the trailing face may be up to 0.53 mm, up to 0.45 mm, up to 0.35 mm.

[77] The width of the trailing face may be from > 0.07 mm to < 0.53 mm, or > 0.18 mm to < 0.45 mm, or > 0.25 mm to < 0.35 mm.

[78] The width of the leading face may be from at least 3.5%, at least 9%, at least 12.5% of the largest width of the spacer member.

[79] The width of the leading face may be up to 26.5%, up to 22.5%, up to 17.5% of the largest width of the spacer member.

[80] The width of the leading face may be from > 3.5% to < 26.5%, or > 9% to < 22.5%, or > 12.5% to < 17.5% of the largest width of the spacer member.

[81] The width of the trailing face may be from at least 3.5%, at least 9%, at least 12.5% of the largest width of the spacer member. [82] The width of the trailing face may be up to 100%, up to 22.5%, up to 17.5% of the largest width of the spacer member.

[83] The width of the trailing face may be from > 3.5% to < 100%, or > 9% to < 22.5%, or > 12.5% to < 17.5% of the largest width of the spacer member.

[84] The largest length of the spacer member may be from at least 0.8 mm, at least 1 .5 mm, at least 2.2 mm.

[85] The largest length of the spacer member may be up to 4 mm, up to 3.5 mm, up to 2.6 mm.

[86] The largest length of the spacer member may be from > 0.8 mm to < 4 mm, or > 1 .5 mm to < 3.5 mm, or > 2.2 mm to < 2.6 mm.

[87] The spacer member may comprise a largest length and a largest width, wherein the largest width may be from at least 0.1 mm, at least 0.2 mm, at least 0.25 mm.

[88] The spacer member may comprise a largest length and a largest width, wherein the largest width may be up to 1 mm, up to 0.5 mm, up to 0.35 mm.

[89] The spacer member may comprise a largest length and a largest width, wherein the largest width may be from > 0.1 mm to < 1 mm, or > 0.2 mm to < 0.5 mm, or > 0.25 mm to < 0.35 mm.

[90] Advantageously, such length to width relationships may provide the spacer member with a substantially elongate form that may further promote a streamlined interaction with the fluid flow.

[91] The height of the spacer member may be from at least 0.25 mm, at least 0.6 mm, at least 0.8 mm..

[92] The height of the spacer member may be up to 2.2 mm, up to 1 .8 mm, up to 1 .2 mm.

[93] The height of the spacer member may be from > 0.25 mm to < 2.2 mm, or > 0.6 mm to < 1 .8 mm, or > 0.8 mm to < 1 .2 mm..

[94] The spacer member may comprise an upper portion and a lower portion, wherein the upper portion is operable to space a membrane component from an upper face of the flow modifier member and the lower portion is operable to space a membrane component from a lower face of the flow modifier member.

[95] The upper and/or lower portion may comprise a front, rear, first side face, second side face, horizontal cross-section and/or dimensions (absolute and/or relative) as previously defined above with respect to the space member.

[96] The upper and lower portions of the spacer member may be substantially vertically aligned, such as substantially concentrically aligned.

[97] The upper and lower portions of the spacer member may be vertically misaligned. The upper and lower portions of the spacer member may not vertically overlap. [98] The feed spacer further comprises a flow modifier member. The flow modifier member is operable to direct the fluid flow toward a membrane component of the spiral wound membrane in the fluid flow channel.

[99] The flow modifier member may be operable to direct the fluid flow toward both adjacent components, i.e., the membrane components above and below the fluid flow member. The flow modifier member may be operable to direct the fluid flow through fluid flow channels formed above and below the flow modifier member by the spacing from the membrane component that is provided by the spacer member.

[100] Advantageously, this arrangement may be operable to improve the efficiency of permeate transfer across adjacent components of the spiral wound membrane. This may increase the turbulence and/or tortuosity of the fluid flow.

[101] The spacer member may project above and below the flow modifier member. For example, the upper portion of the spacer member may project above the flow modifier member and the lower portion of the spacer member may project below the flow modifier member.

[102] The height of the upper and/or lower projecting portion of the spacer member that projects above and/or below the flow modifier member, may be from at least 0.075 mm, at least 0.2 mm, at least 0.27 mm.

[103] The height of the upper and/or lower projecting portion of the spacer member that projects above and/or below the flow modifier member, may be up to 0.31 mm, up to 0.3 mm, up to 0.29 mm.

[104] The height of the upper and/or lower projecting portion of the spacer member that projects above and/or below the flow modifier member, may be from > 0.075 mm to < 0.31 mm, or > 0.2 mm to < 0.3 mm, or > 0.27 mm to < 0.29 mm.

[105] The difference between the height of the upper portion of the spacer member projecting above the flow modifier member and the height of the lower portion of the spacer member projecting below the flow modifier member may be 0 mm.

[106] The difference between the height of the upper portion of the spacer member projecting above the flow modifier member and the height of the lower portion of the spacer member projecting below the flow modifier member may be up to 0.3 mm, up to 0.2 mm, up to 0.1 mm.

[107] The difference between the height of the upper portion of the spacer member projecting above the flow modifier member and the height of the lower portion of the spacer member projecting below the flow modifier member may be from > 0 mm to < 0.3 mm, or > 0 mm to < 0.2 mm, or > 0 mm to < 0.1 mm. [108] The height of the upper and/or lower projecting portion of the spacer member that projects above and/or below the flow modifier member may be from at least 9%, at least 25%, at least 33% of the height of spacer member.

[109] The height of the upper and/or lower projecting portion of the spacer member that projects above and/or below the flow modifier member may be up to 40%, up to 37%, up to 36% of the height of spacer member.

[1 10] The height of the upper and/or lower projecting portion of the spacer member that projects above and/or below the flow modifier member may be from > 9% to < 40%, or > 25% to < 37%, or > 33% to < 36% of the height of spacer member.

[1 11] The flow modifier member may comprise a portion that extends between adjacent spacer members.

[1 12] The flow modifier member, or portion thereof, may comprise a longitudinal axis that is operable to be angularly offset to the direction of the fluid flow.

[1 13] The longitudinal axis of the flow modifier member, or portion thereof, may be operable to be angularly offset to the direction of the fluid flow by an angle from at least 10°, at least 25°, at least 30°.

[1 14] The longitudinal axis of the flow modifier member, or portion thereof, may be operable to be angularly offset to the direction of the fluid flow by an angle of up to 65°, up to 50°, up to 40°.

[1 15] The longitudinal axis of the flow modifier member, or portion thereof, may be operable to be angularly offset to the direction of the fluid flow by an angle from > 10° to < 65°, or > 25° to < 50°, or > 30° to < 40°.

[1 16] The flow modifier member may comprise a leading face and a trailing face. The leading face may be operable to be the first face of the flow modifier member that contacts the fluid flow. The trailing face may be operable to be the last face of the flow modifier member that contacts the fluid flow.

[1 17] The leading face of the flow modifier member may be operable to face relatively upstream into the direction of fluid flow compared to the trailing face. The trailing face may be operable to face substantially downstream of the direction of the fluid flow compared to the leading face.

[1 18] The leading face of the flow modifier member may be curved, such as vertically curved. The curved leading face of the flow modifier member may be curved away from the incoming fluid flow. The curved leading face of the flow modifier member may be curved in the downstream direction. Such a curved leading face may be considered to be convex with respect to the direction of the fluid flow.

[1 19] The leading face of the flow modifier member may be substantially horizontally straight. [120] Advantageously, this arrangement may be operable to provide the flow modifier member with a streamlined leading face, capable of reducing hydraulic resistance and the likelihood of flow separation from occurring downstream of the flow modifier member. The curvature of the leading face of the flow modifier member may promote favourable flow direction toward the adjacent components of the spiral wound membrane. This arrangement may accelerate the fluid flow around the flow modifier member, thereby increasing the turbulence of the fluid flow.

[121] The curved leading face of the flow modifier member may be defined by an arc. The arc defining the curvature of the leading face of the flow modifier member may have a radius of curvature from at least 0.04 mm, at least 0.07 mm, at least 0.09 mm.

[122] The curved leading face of the flow modifier member may be defined by an arc. The arc defining the curvature of the leading face of the flow modifier member may have a radius of curvature of up to 0.3 mm, up to 0.12 mm, up to 0.1 mm.

[123] The curved leading face of the flow modifier member may be defined by an arc. The arc defining the curvature of the leading face of the flow modifier member may have a radius of curvature from > 0.04 mm to < 0.3 mm, or > 0.07 mm to < 0.12 mm, or > 0.09 mm to < 0.1 mm.

[124] The radius of curvature of the leading face of the flow modifier member may be substantially aligned parallel with a lateral axis of the flow modifier member extending along the largest width of the flow modifier member.

[125] The trailing face of the flow modifier member may be operable to promote fluid flow deflection from the flow modifier member toward the adjacent components of the spiral wound membrane. The trailing face may be substantially planar.

[126] The substantially planartrailing face may be substantially vertically orthogonal to the lateral axis of the flow modifier member. In other words, the substantially planar trailing face may be substantially vertically orthogonal to a lateral-longitudinal (horizontal) cross-section of the flow modifier member.

[127] As used herein, ‘substantially vertically orthogonal’ with respect to the lateral axis of the flow modifier member may be from at least 70°, at least 80°, at least 85°.

[128] As used herein, ‘substantially vertically orthogonal’ with respect to the lateral axis of the flow modifier member may be up to 110°, up to 100°, up to 95°.

[129] As used herein, ‘substantially vertically orthogonal’ with respect to the lateral axis of the flow modifier member may be from > 70° to < 1 10°, or > 80° to < 100°, or > 85° to < 95°.

[130] Advantageously, this arrangement may provide the flow modifier member with cross- sectional profile that is operable to direct the fluid flow above and below the flow modifier member and toward the adjacent components of the spiral wound membrane. [131] The height of the lateral-vertical cross-section of the flow modifier member may vary along the lateral axis. In other words, the height of the vertical cross-section of the flow modifier member may vary along its width. For example, the height may be smaller toward the leading face and larger toward the trailing face. The height of the vertical cross-section of the flow modifier member may comprise tapering along the lateral axis from a low toward the leading face to a high toward the trailing face. The flow modifier member may comprise a lateral-vertical cross-section wherein the height of the leading face is smaller than the largest height of the cross-section. The largest height of the cross-section may be toward the trailing face of the cross-section.

[132] The flow modifier member may comprise a substantially wedge-shaped lateral-vertical cross-section.

[133] The lateral-vertical cross-section of the flow modifier member may have a largest height from at least 0.18 mm, at least 0.2 mm, at least 0.22 mm.

[134] The lateral-vertical cross-section of the flow modifier member may have a largest height of up to 0.65 mm, up to 0.4 mm, up to 0.26 mm.

[135] The lateral-vertical cross-section of the flow modifier member may have a largest height from > 0.18 mm to < 0.65 mm, or > 0.2 mm to < 0.4 mm, or > 0.22 mm to < 0.26 mm.

[136] The lateral-vertical cross-section of the flow modifier member may have a lateral axis that extends along the largest width of the lateral-vertical cross-section. The lateral-vertical crosssection may be substantially symmetrical about the lateral axis. The lateral axis may extend between an apex of the leading face and a midpoint of the trailing face.

[137] The lateral-vertical cross-section may have a largest width from at least 0.48 mm, at least 0.9 mm, at least 1 .2 mm.

[138] The lateral-vertical cross-section may have a largest width of up to 2.4 mm, up to 2.1 mm, up to 1 .4 mm.

[139] The lateral-vertical cross-section may have a largest width from > 0.48 mm to < 2.4 mm, or > 0.9 mm to < 2.1 mm, or > 1 .2 mm to < 1 .4 mm.

[140] The flow modifier member may have a lateral-vertical cross-section whereby the width of the cross-section is larger than the height of the cross-section.

[141] Advantageously, this arrangement may be operable to promote direction of the fluid flow around the flow modifier member toward the adjacent components of the spiral wound membrane to increase permeate flux across said components.

[142] The cross-section may have a height that is from at least 10%, or at least 15% of the width.

[143] The cross-section may have a height that is from up to 140%, up to 40%, up to 20% of the width. [144] The cross-section may have a height that is from > 10% to < 140%, or > 10% to < 40%, or 15% to 20% of the width.

[145] Advantageously, this arrangement may be operable to provide the flow modifier member with an elongate form that may further promote a streamlined interaction with the fluid flow.

[146] The feed spacer may comprise a flow modifier member portion that extends from a spacer member. The feed spacer may comprise a flow modifier member portion that extends from an intersection point. The flow modifier member portion may extend between adjacent spacer members and/or adjacent intersection points.

[147] The flow modifier member portion may have a length extending between the adjacent spacer members from at least 1 .5 mm, at least 2 mm, at least 3 mm.

[148] The flow modifier member portion may have a length extending between the adjacent spacer members of up to 6.5 mm, up to 5 mm, up to 4 mm.

[149] The flow modifier member portion may have a length extending between the adjacent spacer members, from > 1 .5 mm to < 6.5 mm, or > 2 mm to < 5 mm, or > 3 mm to < 4 mm.

[150] The flow modifier member portion may have a length extending between the adjacent intersection points of at least 1 .5 mm, at least 2 mm, at least 3 mm.

[151] The flow modifier member portion may have a length extending between the adjacent intersection points of up to 6.5 mm, up to 5 mm, up to 4 mm.

[152] The flow modifier member portion may have a length extending between the adjacent intersection points, from > 1 .5 mm to < 6.5 mm, or > 2 mm to < 5 mm, or > 3 mm to < 4 mm.

[153] The feed spacer may comprise a flow modifier member portion extending between adjacent spacer members, the flow modifier member portion that comprises the lateral-vertical crosssection may be from at least 40%, at least 60%, at least 75%.

[154] The feed spacer may comprise a flow modifier member portion extending between adjacent spacer members, the flow modifier member portion that comprises the lateral-vertical crosssection may be up to 95%, up to 90%, up to 85%.

[155] The feed spacer may comprise a flow modifier member portion extending between adjacent spacer members, the flow modifier member portion that comprises the lateral-vertical crosssection may be from > 40% to < 95%, or > 60% to < 90%, or > 75% to < 85%.

[156] The feed spacer may comprise a flow modifier member comprising a plurality of flow modifier member portions. The spacer member may comprise a flow modifier member the flow modifier member portions that comprises the flow modifier member portion may be from at least 40%, at least 60%, at least 75%. [157] The feed spacer may comprise a flow modifier member comprising a plurality of flow modifier member portions. The spacer member may comprise a flow modifier member the flow modifier member portions that comprises the flow modifier member portion may be up to 95%, up to 90%, up to 85%.

[158] The feed spacer may comprise a flow modifier member comprising a plurality of flow modifier member portions. The spacer member may comprise a flow modifier member the flow modifier member portions that comprises the flow modifier member portion may be from > 40% to < 95%, or > 60% to < 90%, or > 75% to < 85%.

[159] The feed spacer may comprise a flow modifier member, the portion of the flow modifier member that comprises the lateral-vertical cross-section, may be from at least 40%, at least 60%, at least 75%.

[160] The feed spacer may comprise a flow modifier member, the portion of the flow modifier member that comprises the lateral-vertical cross-section, may be up to 95%, up to 90%, up to 85%.

[161] The feed spacer may comprise a flow modifier member, the portion of the flow modifier member that comprises the lateral-vertical cross-section, may be from > 40% to < 95%, or > 60% to < 90%, or > 75% to < 85%.

[162] The flow modifier member, or portion thereof, may have an average largest height from at least 0.18 mm, at least 0.2 mm, at least 0.22 mm.

[163] The flow modifier member, or portion thereof, may have an average largest height up to 0.65 mm, up to 0.4 mm, up to 0.26 mm.

[164] The flow modifier member, or portion thereof, may have an average largest height from > 0.18 mm to < 0.65 mm, or > 0.2 mm to < 0.4 mm, or > 0.22 mm to < 0.26 mm.

[165] The average height of the leading face of the flow modifier member, or portion thereof, may be from at least 0.07 mm, 0.1225 mm, at least 0.1575 mm.

[166] The average height of the leading face of the flow modifier member, or portion thereof, may be up to 0.525 mm, up to 0.21 mm, up to 0.175 mm.

[167] The average height of the leading face of the flow modifier member, or portion thereof, may be from > 0.07 mm to < 0.525 mm, or > 0.1225 mm to < 0.21 mm, or > 0.1575 mm to < 0.175 mm.

[168] The average height of the leading face of the flow modifier member, or portion thereof, may be from at least 10%, at least 20%, at least 22% of the height of the spacer member.

[169] The average height of the leading face of the flow modifier member, or portion thereof, may be up to 70%, up to 35%, up to 30% of the height of the spacer member. [170] The average height of the leading face of the flow modifier member, or portion thereof, may be from > 10% to < 70%, or > 20% to < 35%, or > 22% to < 30% of the height of the spacer member.

[171] The average height of the trailing face of the flow modifier member, or portion thereof, may be from at least 0.18 mm, at least 0.2 mm, at least 0.22 mm.

[172] The average height of the trailing face of the flow modifier member, or portion thereof, may be up to 0.65 mm, up to 0.4 mm, up to 0.26 mm.

[173] The average height of the trailing face of the flow modifier member, or portion thereof, may be from > 0.18 mm to < 0.65 mm, or > 0.2 mm to < 0.4 mm, or > 0.22 mm to < 0.26 mm.

[174] The average height of the trailing face of the flow modifier member, or portion thereof, may be from at least 22.5%, at least 25%, at least 27.5% of the height of the spacer member.

[175] The average height of the trailing face of the flow modifier member, or portion thereof, may be up to 81 .25%, up to 50%, up to 32.5% of the height of the spacer member.

[176] The average height of the trailing face of the flow modifier member, or portion thereof, may be from > 22.5% to < 81 .25%, or > 25% to < 50%, or > 27.5% to < 32.5% of the height of the spacer member.

[177] The average height of the leading face of the flow modifier member, or portion thereof, may be from at least 15%, at least 40%, at least 60% of the height of the trailing face of the flow modifier member.

[178] The average height of the leading face of the flow modifier member, or portion thereof, may be up to 90%, up to 85%, up to < 80% of the height of the trailing face of the flow modifier member.

[179] The average height of the leading face of the flow modifier member, or portion thereof, may be from > 15% to < 90%, or > 40% to < 85%, or > 60% to < 80% of the height of the trailing face of the flow modifier member.

[180] Advantageously, these characteristics may increase the extent to which the fluid flow may be directed toward the adjacent components of the spiral wound membrane by the flow modifier member. This arrangement may also be operable to increase the turbulence and/or tortuosity of fluid flow.

[181] The flow modifier member may further comprise an upper face. The upper face may extend between an upper end of the leading face and an upper end of the trailing face. The upper face may be substantially planar. The upper face may be operable to face substantially toward the upper component of the adjacent components of the spiral wound membrane.

[182] The upper face of the flow modifier member (or for a non-planar upper face a plane extending between the start and end points of the upper face) may be angled at least 3°, at least 4°, at least 5° from the lateral axis of the flow modifier member. [183] The upper face of the flow modifier member (or for a non-planar upper face a plane extending between the start and end points of the upper face) may be angled up to 30°, up to 15°, up to 10° from the lateral axis of the flow modifier member.

[184] The upper face of the flow modifier member (or for a non-planar upper face a plane extending between the start and end points of the upper face) may be angled at > 3° to < 30°, or

> 4° to < 15°, or > 5° to < 10° from the lateral axis of the flow modifier member.

[185] The flow modifier member may further comprise a lower face. The lower face may extend between a lower end of the leading face and a lower end of the trailing face. The lower face may be substantially planar. The lower face may face substantially toward the lower component of the adjacent components of the spiral wound membrane.

[186] The lower face of the flow modifier member (or for a non-planar lower face a plane extending between the start and end points of the lower face) may be angled at least > 3°, at least 4°, at least 5° from the lateral axis of the flow modifier member.

[187] The lower face of the flow modifier member (or for a non-planar lower face a plane extending between the start and end points of the lower face) may be angled up to 30°, up to 15°, up to 10° from the lateral axis of the flow modifier member.

[188] The lower face of the flow modifier member (or for a non-planar lower face a plane extending between the start and end points of the lower face) may be angled at > 3° to < 30°, or

[189] Advantageously, angling of the upper and/or lower faces of the flow modifier member may promote deflection of the fluid flow towards adjacent components of the spiral wound membrane.

[190] The flow modifier member may comprise a bulged portion operable to increase the lateral and vertical turbulence of the fluid flow compared to another part of the flow modifier member, or portion thereof extending between adjacent spacer members. In other words, the bugled portion may be operable to increase the lateral and vertical turbulence of the fluid flow compared to a non-bulged portion of the flow modifier member.

[191] A bulged portion of the flow modifier member may comprise a substantially vertically extending projection, such as in the upper and/or lower face. A bulged portion of the flow modifier member may comprise outwardly extending, or convex, curvature in the upper and/or lower face at the part of the bulged portion. The bulged portion may be arranged proximate to the middle of the flow modifier member portion in the longitudinal direction relative to the ends of the flow modifier member portion.

[192] The flow modifier member, or a portion thereof, may comprise a longitudinal-vertical crosssection wherein the largest height of the longitudinal-vertical cross-section may be > 30% along the length of the longitudinal-vertical cross-section from an adjacent intersection. The largest height of the longitudinal-vertical cross-section may be < 70% along the length of the longitudinalvertical cross-section from an adjacent intersection.

[193] The flow modifier member, or a portion thereof, may comprise a series of lateral-vertical cross-sections in an X-Y-Z sequence along its length. The lateral-vertical cross-section Y may have a larger height than the lateral-vertical cross-sections of X or Z.

[194] The series of X, Y, and Z cross-sections may be substantially evenly spatially separated along the longitudinal-vertical cross-section of the flow modifier member, or a portion thereof. The X and Z cross-sections may be more proximate to the adjacent spacer members or intersections than cross-section Y.

[195] A bulged portion may not be operable to contact the membrane component in use.

[196] The bulged portion may comprise a height that is larger than the average height of the flow modifier member, or portion thereof.

[197] The largest height of the bulged portion may be from > 50% to < 250%, or> 70% to < 190%, or > 80% to < 150% larger than the average height of the flow modifier member, or portion thereof.

[198] The largest height of the bulged portion may be from at least 50%, at least 70%, at least 80% larger than the average height of the flow modifier member, or portion thereof.

[199] The largest height of the bulged portion may be up to 250%, up to 190%, up to 150% larger than the average height of the flow modifier member, or portion thereof.

[200] The largest height of the bulged portion may be from > 50% to < 250%, or > 70% to < 190%, or > 80% to < 150% larger than the average height of the flow modifier member, or portion thereof. The largest height of the bulged portion may be from at least 80%, at least 120%, at least 150% larger than the smallest height of the flow modifier member, or portion thereof.

[201] The largest height of the bulged portion may be up to 320%, up to 280%, up to 230% larger than the smallest height of the flow modifier member, or portion thereof.

[202] The largest height of the bulged portion may be from > 80% to < 320%, or > 120% to < 280%, or > 150% to < 230% largerthan the smallest height of the flow modifier member, or portion thereof.

[203] The largest height of the bulged portion may be from at least 38%, at least 50%, at least 56% of the height of the spacer member.

[204] The largest height of the bulged portion may be up to 88%, up to 81 %, up to 70% of the height of the spacer member.

[205] The largest height of the bulged portion may be from > 38% to < 88%, or > 50% to < 81 %, or > 56% to < 70% of the height of the spacer member. [206] The flow modifier member, or a portion thereof, may comprise a first lateral-vertical crosssection and a second lateral-vertical cross-section. The second lateral-vertical cross-section may have a larger height than the first lateral-vertical cross-section.

[207] The first lateral-vertical cross-section may have height from at least 0.18 mm, at least 0.2 mm, at least 0.22 mm.

[208] The first lateral-vertical cross-section may have height of up to 0.45 mm, up to 0.4 mm, up to 0.26 mm.

[209] The first lateral-vertical cross-section may have height from > 0.18 mm to < 0.45 mm, or > 0.2 mm to < 0.4 mm, or > 0.22 mm to < 0.26 mm.

[210] The second lateral-vertical cross-section may have height from at least 0.3 mm, at least 0.35 mm, at least 0.4 mm.

[211] The second lateral-vertical cross-section may have height of up to 0.65 mm, up to 0.6 mm, up to 0.55 mm.

[212] The second lateral-vertical cross-section may have height from at least 0.3 mm, at least 0.35 mm, at least 0.4 mm.

[213] The second lateral-vertical cross-section may have height of up to 0.65 mm, up to 0.6 mm, up to 0.55 mm.

[214] The second lateral-vertical cross-section may have height from > 0.3 mm to < 0.65 mm, or > 0.35 mm to < 0.6 mm, or > 0.4 mm to < 0.55 mm.

[215] The second lateral-vertical cross-section may have a height from at least 110%, at least 130%, at least 150% of the height of the first lateral-vertical cross-section.

[216] The second lateral-vertical cross-section may have a height of up to 350%, up to 300%, up to 250% of the height of the first lateral-vertical cross-section.

[217] The second lateral-vertical cross-section may have a height from > 110% to < 350%, or > 130% to < 300%, or > 150% to < 250% of the height of the first lateral-vertical cross-section.

[218] The first lateral-vertical cross-section may have a height from at least 23%, at least 25%, at least 27% of the height of the spacer member.

[219] The first lateral-vertical cross-section may have a height of up to 56%, up to 50%, up to 32% of the height of the spacer member.

[220] The first lateral-vertical cross-section may have a height from > 23% to < 56%, or > 25% to < 50%, or > 27% to < 32% of the height of the spacer member.

[221] The second lateral-vertical cross-section may have a height from at least 37%, at least 43%, at least 50% of the height of the spacer member.

[222] The second lateral-vertical cross-section may have a height of up to 81%, up to 75%, up to 68% of the height of the spacer member. [223] The second lateral-vertical cross-section may have a height from > 37% to < 81%, or > 43% to < 75%, or > 50% to < 68% of the height of the spacer member.

[224] The flow modifier member, or portion thereof, may comprise at least 30%, at least 35%, at least 40% of the first lateral vertical cross-section.

[225] The flow modifier member, or portion thereof, may comprise up to 60%, up to 55%, up to 50% of the first lateral vertical cross-section.

[226] The flow modifier member, or portion thereof, may comprise > 30% to < 60%, or > 35% to

< 55%, or > 40% to < 50% of the first lateral-vertical cross-section.

[227] The flow modifier member, or portion thereof, may comprise at least 20%, at least 25%, at least 30% of the second lateral-vertical cross-section.

[228] The flow modifier member, or portion thereof, may comprise up to 50%, up to 45%, up to 40% of the second lateral-vertical cross-section.

[229] The flow modifier member, or portion thereof, may comprise > 20% to < 50%, or > 25% to

< 45%, or > 30% to < 40% of the second lateral-vertical cross-section.

[230] The flow modifier member, or a portion thereof, may comprise a longitudinal-vertical crosssection. The longitudinal-vertical cross-section may extend between adjacent spacer members.

[231] The flow modifier member may comprise a first longitudinal-vertical cross-section and a second longitudinal-vertical cross-section. The second longitudinal-vertical cross-section may have a larger height than the first longitudinal lateral-vertical cross-section.

[232] The first longitudinal-vertical cross-section may be operable to be closer to the leading face of the flow modifier memberthan the second longitudinal-vertical cross-section of the flow modifier member.

[233] The trailing face of the flow modifier member may comprise the second longitudinal-vertical cross-section.

[234] The first longitudinal-vertical cross-section may have a height that is substantially the same or constant along its length.

[235] The first longitudinal-vertical cross-section may have a height that deviates from a mean average of the height of the flow modifier member, or portion thereof, by a small deviation. The first longitudinal-vertical cross-section may have a height that deviates from a mean average height of the flow modifier member, or portion thereof by < 20%, such as < 10, or < 5%.

[236] The first longitudinal-vertical cross-section may have height from at least 0.15 mm, at least 0.2 mm, at least 0.25 mm.

[237] The first longitudinal-vertical cross-section may have height of up to 0.4 mm, up to 0.35 mm, up to 0.3 mm.

[238] The first longitudinal-vertical cross-section may have height from > 0.15 mm to < 0.4 mm, or > 0.2 mm to < 0.35 mm, or > 0.25 mm to < 0.3 mm. [239] The second longitudinal-vertical cross-section may have height from at least 0.3 mm, at least 0.35 mm, at least 0.4 mm.

[240] The second longitudinal-vertical cross-section may have height of up to 0.65 mm, up to 0.6 mm, up to 0.55 mm.

[241] The second longitudinal-vertical cross-section may have height from > 0.3 mm to < 0.65 mm, or > 0.35 mm to < 0.6 mm, or > 0.4 mm to < 0.55 mm.

[242] The second longitudinal-vertical cross-section may have a height from at least 120%, at least 160%, at least 180% of the height of the first longitudinal vertical cross-section.

[243] The second longitudinal-vertical cross-section may have a height of up to 300%, up to 250%, up to 230% of the height of the first longitudinal-vertical cross-section.

[244] The second longitudinal-vertical cross-section may have a height from > 120% to < 300%, or > 160% to < 250%, or > 180% to < 230% of the height of the first longitudinal-vertical crosssection.

[245] The first longitudinal-vertical cross-section may have a height from at least 18%, at least 25%, at least 30% of the height of the spacer member.

[246] The first longitudinal-vertical cross-section may have a height of up to 50%, up to 45%, up to 40% of the height of the spacer member.

[247] The first longitudinal-vertical cross-section may have a height from > 18% to < 50%, or > 25% to < 45%, or > 30% to < 40% of the height of the spacer member.

[248] The second longitudinal-vertical cross-section may have a height from at least 37.5%, at least 43.75%, at least 50% of the height of the spacer member.

[249] The second longitudinal-vertical cross-section may have a height of up to 81.25%, up to 75%, up to 68.75% of the height of the spacer member.

[250] The second longitudinal-vertical cross-section may have a height from > 37.5% to < 81.25%, or > 43.75% to < 75%, or > 50% to < 68.75% of the height of the spacer member.

[251] The flow modifier member, or portion thereof, may comprise from at least 30%, at least 35%, at least 40% of the first longitudinal-vertical cross-section.

[252] The flow modifier member, or portion thereof, may comprise up to 60%, up to 55%, up to 50% of the first longitudinal-vertical cross-section.

[253] The flow modifier member, or portion thereof, may comprise from > 30% to < 60%, or > 35% to < 55%, or > 40% to < 50% of the first longitudinal-vertical cross-section.

[254] The flow modifier member, or portion thereof, may comprise from at least 20%, at least 25%, at least 30% of the second longitudinal-vertical cross-section. [255] The flow modifier member, or portion thereof, may comprise up to 50%, up to 45%, up to 40% of the second longitudinal-vertical cross-section.

[256] The flow modifier member, or portion thereof, may comprise from > 20% to < 50%, or > 25% to < 45%, or > 30% to < 40% of the second longitudinal-vertical cross-section.

[257] Advantageously, the bulged portion may provide favourable flow dynamics around the flow modifier member by increasing fluid velocity and directing the fluid flow toward the adjacent components.

[258] The feed spacer may comprise a plurality of flow modifier members, such as > 10, or > 50, or > 100.

[259] The spacer member may comprise a plurality of flow modifier members wherein the longitudinal axes are substantially aligned parallel.

[260] As used herein, ‘substantially aligned parallel’ with respect to the longitudinal axis of each of the flow modifier members from the plurality of flow modifier members may be < 10°, such as < 5°, or < 2° from parallel with the longitudinal axis of the adjacent flow modifier member.

[261] Advantageously, this arrangement may be operable to increase fluid flow direction toward the adjacent components of the spiral wound membrane.

[262] The spacing between adjacent flow modifier members may be larger or smaller closer to the edges of the feed spacer. The spacing between the adjacent flow modifier members may be substantially constant across a majority of the feed spacer. The spacing between the adjacent flow modifier members may be substantially constant across from at least 70%, at least 75%, at least 80% of the feed spacer.

[263] The spacing between adjacent flow modifier members may be larger or smaller closer to the edges of the feed spacer. The spacing between the adjacent flow modifier members may be substantially constant across a majority of the feed spacer. The spacing between the adjacent flow modifier members may be substantially constant across up to 95%, up to 92%, up to 90% of the feed spacer.

[264] The spacing between adjacent flow modifier members may be larger or smaller closer to the edges of the feed spacer. The spacing between the adjacent flow modifier members may be substantially constant across a majority of the feed spacer. The spacing between the adjacent flow modifier members may be substantially constant across from > 70% to < 95%, or > 75% to < 92%, or > 80% to < 90% of the feed spacer.

[265] The feed spacer may comprise intersecting flow modifier members. In other words, the longitudinal axes of flow modifier members may intersect with each other.

[266] The longitudinal axes of the intersecting flow modifier members may be angularly offset relative to each other by an angle of at least 20°, at least 50°, at least 60°. [267] The longitudinal axes of the intersecting flow modifier members may be angularly offset relative to each other by an angle of up to 130°, up to 100°, up to 80°.

[268] The longitudinal axes of the intersecting flow modifier members may be angularly offset relative to each other by an angle of > 20° to < 130°, or > 50° to < 100°, or > 60° to < 80°.

[269] The feed spacer may comprise a flow modifier member that is intersected by a plurality of flow modifier members, such as intersected at spaced intervals.

[270] Advantageously, this arrangement may improve direction of the flow toward the adjacent components of the spiral wound membrane. This arrangement may further be operable to pack more flow modifier members into the feed spacer.

[271] The feed spacer may comprise a first series and a second series of flow modifier members, wherein each series comprises a plurality of flow modifier members. The first series of flow modifiers members may comprise a plurality of at least partially spaced and substantially parallelly aligned flow modifier members. The second series of flow modifier members may comprise a plurality of at least partially spaced and substantially parallelly aligned flow modifier members.

[272] Advantageously, this arrangement may be operable to allow flow modifier members to be arranged in groups that may be arranged relative to one another so as to provide improved flow direction, turbulence and/or tortuosity.

[273] The flow modifier members of the first and/or second series of flow modifier members may be spatially separated from each other in a lateral direction relative to the feed spacer. The spatial separation between adjacent flow modifier members may create fluid flow channels through which the fluid may flow.

[274] The flow modifier members of the first and/or second series of flow modifier members may be laterally separated from each other by a distance from at least 2 mm, at least 3 mm, at least 3.5 mm.

[275] The flow modifier members of the first and/or second series of flow modifier members may be laterally separated from each other by a distance of up to 7 mm, up to 6 mm, up to 5 mm.

[276] The flow modifier members of the first and/or second series of flow modifier members may be laterally separated from each other by a distance from > 2 mm to < 7 mm, or > 3 mm to < 6 mm, or > 3.5 mm to < 5 mm.

[277] The average separation distance between adjacent flow modifier members of the first series of flow modifier members may be from at least 2 mm, at least 3 mm, at least 3.5 mm.

[278] The average separation distance between adjacent flow modifier members of the first series of flow modifier members may be up to 7 mm, up to 6 mm, up to 5 mm. [279] The average separation distance between adjacent flow modifier members of the first series of flow modifier members may be from > 2 mm to < 7 mm, or > 3 mm to < 6 mm, or > 3.5 mm to < 5 mm.

[280] The average separation distance between adjacent flow modifier members of the second series of flow modifier members may be from at least 2 mm, at least 3 mm, at least 3.5 mm.

[281] The average separation distance between adjacent flow modifier members of the second series of flow modifier members may be up to 7 mm, up to 6 mm, up to 5 mm.

[282] The average separation distance between adjacent flow modifier members of the second series of flow modifier members may be from > 2 mm to < 7 mm, or > 3 mm to < 6 mm, or > 3.5 mm to < 5 mm.

[283] Advantageously, this arrangement may provide the feed spacer with a plurality of surfaces that may be arranged relative to each other that may be operable to promote the disruption and redirection of the fluid flow toward the adjacent components of the spiral wound membrane.

[284] The flow modifier members of the first series may comprise a shared longitudinal axis that extends along the length of the collective orientation of the series. The flow modifier members of the second series may comprise a shared longitudinal axis that extends along the length of the collective orientation of the series.

[285] The shared longitudinal axes of the first and/or second series flow modifier member may be operable to be angularly offset to direction of the fluid flow.

[286] Advantageously, this arrangement may provide the feed spacer with a plurality of flow modifier members arranged relative to each other to promote the direction of the fluid flow toward the adjacent components of the spiral wound membrane. This arrangement may further increase the tortuosity of the flow pathway taken by the fluid flow.

[287] The shared longitudinal axis of the first and/or second series may be operable to be angularly offset by an angle from at least 20°, at least to 50°, at least 60°.

[288] The shared longitudinal axis of the first and/or second series may be operable to be angularly offset by an angle of up to 130°, up to 100°, up to 80°.

[289] The shared longitudinal axis of the first and/or second series may be operable to be angularly offset by an angle from > 20° to < 130°, or > 50° to < 100°, or > 60° to < 80°.

[290] The shared longitudinal axis of the first and/or second series may be operable to be angularly offset to the direction of the fluid flow by an angle from at least 10°, at least 25°, at least 30°.

[291] The shared longitudinal axis of the first and/or second series may be operable to be angularly offset to the direction of the fluid flow by an angle of up to 65°, up to 50°, up to 40°. [292] The shared longitudinal axis of the first and/or second series may be operable to be angularly offset to the direction of the fluid flow by an angle from > 10° to < 65°, or > 25° to < 50°, or > 30° to < 40°.

[293] Advantageously, this arrangement of the flow modifier members may enable redirection of the fluid flow passing through the feed spacer.

[294] The second series of flow modifier members, or shared longitudinal axis thereof, may be angularly offset relative to the first series of flow modifier members, or shared longitudinal axis thereof. In other words, the shared longitudinal axis of the second series of flow modifier members may be angularly offset relative to the shared longitudinal axis of the first series of flow modifier members.

[295] The shared longitudinal axis of the first series may be angularly offset relative to the shared longitudinal axis of the second series by an angle from at least 20°, at least 50°, at least 60°.

[296] The shared longitudinal axis of the first series may be angularly offset relative to the shared longitudinal axis of the second series by an angle of up to 130°, up to 100°, up to 80°.

[297] The shared longitudinal axis of the first series may be angularly offset relative to the shared longitudinal axis of the second series by an angle from > 20° to < 130°, or > 50° to < 100°, or > 60° to < 80°.

[298] The flow modifier members of the first series may intersect with the flow modifier members of the second series.

[299] Advantageously, this arrangement promotes turbulent flow and may increase the tortuosity of the fluid flow path.

[300] The feed spacer may comprise a plurality of spacer members, such as > 50, or > 200 or > 500.

[301] The feed spacer may comprise a spacer member at an intersection between flow modifier members. The feed spacer may comprise a spacer member at > 70% of the intersections between flow modifier members, such as > 80%, or > 90%.

[302] Advantageously, this arrangement may provide a consistent separation between adjacent components of the spiral wound membrane across the whole area of the feed spacer. This arrangement may be operable to promote favourable flow dynamics. This arrangement may further prevent sagging of the membrane material.

[303] The flow modifier member, or portion thereof, may have a height that is less than the height of the spacer member, such as the adjacent spacer members.

[304] Advantageously, this arrangement may be operable to provide spacing between the flow modifier member and the adjacent component of the spiral wound membrane. The spacing provided above and below the flow modifier member may enable fluid flow to be directed the adjacent components of the spiral wound membrane, thereby increasing permeate flux across adjacent components of the spiral wound membrane.

[305] The average distance between laterally adjacent spacer members may be from at least 2 mm, at least 3 mm, at least 3.5 mm.

[306] The average distance between laterally adjacent spacer members may be up to 7 mm, up to 6 mm, up to 5 mm.

[307] The average distance between laterally adjacent spacer members may be from > 2 mm to < 7 mm, or > 3 mm to < 6 mm, or > 3.5 mm to < 5 mm.

[308] The average distance between longitudinally adjacent spacer members may be from at least 2 mm, at least 3 mm, at least 3.5 mm.

[309] The average distance between longitudinally adjacent spacer members may be up to 7 mm, up to 6 mm, up to 5 mm.

[310] The average distance between longitudinally adjacent spacer members may be from > 2 mm to < 7 mm, or > 3 mm to < 6 mm, or > 3.5 mm to < 5 mm.

[311] The average spatial density of spacer members across the feed spacer may be from at least 4 cm'², at least 6 cm'², at least 8 cm ².

[312] The average spatial density of spacer members across the feed spacer may be up to 36 cm'², up to 20 cm'², up to 10 cm ².

[313] The average spatial density of spacer members across the feed spacer may be from > 4 cm ² to < 36 cm'², or > 6 cm ² to < 20 cm'², or > 8 cm^-2 to < 10 cm ².

[314] The spacer member may be attached to the respective flow modifier members intersection point. The spacer member may be integrally formed with the respective intersection point.

[315] Advantageously, an integrated arrangement may improve the strength and stability of the feed spacer.

[316] The flow modifier member may project from a side face of a spacer member. The spacer member may project from an upper and/or lower face of a flow modifier member.

[317] The longitudinal axis of the flow modifier member, or portion thereof, may be angularly offset to the longitudinal axis of the spacer member, such as an adjacent spacer member, such as off-set at an angle from at least 10°, at least 25°, at least to 30°.

[318] The longitudinal axis of the flow modifier member, or portion thereof, may be angularly offset to the longitudinal axis of the spacer member, such as an adjacent spacer member, such as off-set at an angle of up to 65°, up to 50°, up to 40°. [319] The longitudinal axis of the flow modifier member, or portion thereof, may be angularly offset to the longitudinal axis of the spacer member, such as an adjacent spacer member, such as off-set at an angle from > 10° to < 65°, or > 25° to < 50°, or > 30° to < 40°.

[320] Advantageously, this arrangement may be operable to provide a flow path around the flow modifier member whilst enabling a larger surface area of the adjacent spiral wound membrane component to be in contact with the fluid flow.

[321] The feed spacer may comprise a spacer member having a height that is larger than the average height of an adjacent flow modifier member portion that extends between the spacer member and an adjacent spacer member. The spacer member may have a height that is larger than the average height of at least two adjacent flow modifier member portions, such as at least three or at least four.

[322] The height of the spacer member may be from at least 30%, at least 70%, at least 100% larger than the average height of an adjacent flow modifier member portion that extends between the spacer member and an adjacent spacer member.

[323] The height of the spacer member may be up to 350%, up to 300%, up to 250% larger than the average height of an adjacent flow modifier member portion that extends between the spacer member and an adjacent spacer member.

[324] The height of the spacer member may be from > 30% to < 350%, or > 70% to < 300%, or > 100% to < 250% larger than the average height of an adjacent flow modifier member portion that extends between the spacer member and an adjacent spacer member.

[325] Advantageously, this arrangement may be operable to prevent flow paths through the feed spacer from being blocked by the flow modifier members. This arrangement may further provide spacing between the adjacent components of the spiral wound membrane for fluid to pass.

[326] The difference between the height of the spacer member and the average height of the flow modifier member, or portion thereof, may be from at least 0.2 mm, at least 0.3 mm, at least 0.45 mm.

[327] The difference between the height of the spacer member and the average height of the flow modifier member, or portion thereof, may be up to 0.62 mm, up to 0.6 mm, up to 0.55 mm.

[328] The difference between the height of the spacer member and the average height of the flow modifier member, or portion thereof, may be from > 0.2 mm to < 0.62 mm, or > 0.3 mm to < 0.6 mm, or > 0.45 mm to < 0.55 mm.

[329] The feed spacer may comprise intersecting flow modifier members, wherein the intersecting flow modifier members are in substantially the same horizontal plane.

[330] The feed spacer may comprise a plurality of intersecting flow modifier members substantially the same horizontal plane. [331] The first and second series of flow modifier members may be in substantially the same horizontal plane.

[332] At least 50% of the flow modifier members, or portions thereof, may be in substantially the same horizontal plane, such as > 75%, or > 90%.

[333] As used herein, ‘substantially the same horizontal plane’ may mean that there is at least some horizontal co-planar overlap between lateral-vertical cross-sections of the intersecting flow modifier members, such as > 25%, or > 50%, or > 75%, > 85%, or > 95% overlap.

[334] Advantageously, the planar arrangement may be operable to reduce hydraulic resistance provided by the plurality of flow modifier members, and to reduce the pressure drop across the spiral wound membrane.

[335] According to an aspect of the present invention, there is provided a feed spacer for a spiral wound membrane, such as for water filtration, comprising: a. a spacer member operable to space apart adjacent components of the spiral wound membrane to form a fluid flow channel; and b. a flow modifier member operable to direct fluid flow toward a membrane component of the spiral wound membrane in the fluid flow channel, wherein the spacer member is operable to space the membrane component from the flow modifier member so as to form a fluid flow channel above and below the flow modifier member, wherein the spacer member comprises a substantially oval-shaped horizontal crosssection, wherein the flow modifier member comprises a substantially wedge-shaped lateral-vertical cross-section.

[336] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be operable to provide a transmembrane pressure from > 10 bar to < 120 bar for reverse osmosis membrane modules.

[337] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be operable to provide a transmembrane pressure from > 5 bar to < 60 bar for nanofiltration membrane modules.

[338] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be operable to provide a transmembrane pressure from > 3 bar to < 40 bar for ultrafiltration membrane modules. [339] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be operable to provide a transmembrane pressure from > 1 bar to < 10 bar for microfiltration membrane modules.

[340] As used herein, a ‘comparative component’ may be a feed spacer formed from an overlaid cylindrical mesh. The overlaid cylindrical mesh may be formed from a first layer of cylindrical struts and a second layer of cylindrical struts. The struts of the first and second layers may be arranged substantially orthogonally to each other. The diameter of the struts may be approximately 0.5 mm.

[341] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be operable to provide a permeate flux in a spiral wound membrane that is > 5% higher than a comparative component such as > 20%, or > 40%.

[342] The feed spacer for a spiral wound membrane according to any aspect of the present invention may have packing density of < 1800 m²/m³, such as < 1500 m²/m³, such as < 1200 m²/m³.

[343] The feed spacer for a spiral wound membrane according to any aspect of the present invention may have packing density of > 300 m²/m³, such as > 600 m²/m³, such as > 800 m²/m³.

[344] The feed spacer for a spiral wound membrane according to any aspect of the present invention may have a packing density that is > 5% higher compared to a comparative component, such as > 25% or > 50%.

[345] As used herein, packing density was calculated as follows:

Total area of the membrane

Packing density = — - - - - - - - — —

Volume of spiral wound module

[346] For example, for a spiral wound module, the packing density was calculated as follows;

Dimensional measurements are made of:

A = n * 2 * W * L

L = Longitudinal length of spiral wound module n = No. Of leaves of membrane

D = Diameter of the spiral wound module

W = Unwound width of the membrane leaf

[347] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be operable to provide a > 5% reduction of pressure drop in a spiral wound membrane compared to a comparative component, more preferably > 20%, most preferably > 30%.

[348] The feed spacer for a spiral wound membrane according to any aspect of the present invention may have an active surface area that is > 5% higher than a comparative component, more preferably > 30%, such as > 50%.

[349] References herein to “comparative component”, unless provided otherwise, refer to a comparative feed spacer component in the same spiral wound membrane under the same conditions as the feed spacer of the present invention.

[350] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be prepared by additive manufacturing.

[351] According to an aspect of the present invention, there is provided a method of preparing a feed spacer comprising the steps of: a. producing a feed spacer component, optionally comprising a support material, by additive manufacturing; b. removing the optional support material by dissolving the support material with a solvent , or by mechanically removing the support material; c. optionally UV-curing the feed spacer component.

[352] The additive manufacturing technique may be any suitable 3D printing technology. For example, the feed spacer for a spiral wound membrane according to any aspect of the present invention may be printed using stereolithography, digital light processing, two-photon polymerisation, two colour photo-polymerisation, inkjet printing, binder jet printing, stereolithography (SLA), direct ink writing, three-dimensional printing, selective laser sintering, selective laser melting, laminated object manufacturing, or fused deposition modelling.

[353] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be prepared by inkjet printing, more specifically, material jetting 3D printing.

[354] The feed spacer for a spiral wound membrane according to any aspect of the present invention may comprise a polymeric material, a ceramic material, a composite material, an inorganic-organic material and/or a metal material.

[355] The feed spacer for a spiral wound membrane according to any aspect of the present invention may be formed from materials selected from UV cured thermoset precursor materials; polycarbonate based materials such as Accura 5530, Accura 60, Accura 55; acrylonitrile butadiene styrene based materials such as Renshape SL7820, Somos Watershed XC 11122, Accura Xtreme White 200, Somos 14120; polypropylene based materials such as Somos 9120, Acurra 25, Samos NeXT; polyethylene based materials such as VisiJet SL Flex; epoxy based materials such as Epoxy SL5170; acrylic based materials such as Accura Xtreme, Accura Xtreme 200; resin materials such as a glass-filled Rigid 4000 resin, or any combination thereof.

[356] The present invention may include the step of washing the feed spacer component with any suitable solvent known to the skilled person, such as a polar solvent or non-polar solvent, such as isopropyl alcohol.

[357] Advantageously, the feed spacer for a spiral wound membrane of the present invention can produced with improved ease of processing and/or low cost.

[358] The feed spacer according to the aspects of the present invention may be utilised in a wide range of architectures and filtration devices, including but not limited to those working under gravity filtration, vacuum filtration and/or pressurised systems.

[359] The feed spacer of any aspect of the present invention may be for any type of filtration. Suitably, the feed spacer of the present invention is for water treatment, such as oil/water separation; molecule separation, pharmaceutical filtration for removal of pharmaceutical residues in the aquatic environment; biofiltration, for example separation between micro-organisms and water; desalination or selective ion filtration for extraction of precious metals such as Lithium; and nuclear waste water filtration for removal of nuclear radioactive elements from nuclear waste water; for blood treatment such as physiological filtration to replace damaged kidney filter and blood filtration; and/or separation of bio-platform molecules derived from sources such as plants, for example a grass. Suitably the feed spacer is for water treatment, such as desalination or oil and water separation, or for pharmaceutical filtration.

[360] As used herein, the radius of curvature is:

1

R = - K

Wherein R is the radius of curvature, and x is the curvature of the arc.

[361] Using this definition, the radius of curvature at any point on curve is the radius of an osculating circle at that point. When the curve is a circle, the radius of curvature is radius of the circle at all its points.

[362] As used herein, turbulence was measured using the Reynolds number (Re):

Wherein p is the density of the fluid, u is the velocity of the fluid flow, L is the characteristic linear dimension, and p is the dynamic viscosity of the fluid.

[363] As used herein, tortuosity was measured by:

T = C /L Wherein T is the tortuosity of the fluid flow, C is the length of a streamline between a first and second point, L is the straight-line distance between the first and second point.

[364] As used herein, hydraulic resistance was measured by:

Wherein AP is the pressure drop across a periodic section, p is density of the fluid and v_avg is the average velocity of the fluid flow.

[365] As used herein, a uniformity of velocity distribution was measured by:

Wherein v, is local velocity through unit area A. There are n number of unit areas through which this local velocity is calculated such that addition of these discrete areas is equal to the total available area of the membrane components, and v_a is the average velocity through this total area.

[366] As used herein, unless otherwise expressly specified, all numbers such as those expressing values, ranges, amounts or percentages may be read as if prefaced by the word “about”, even if the term does not expressly appear. The term “about” when used herein means +/- 10% of the stated value.

[367] Also, any numerical range recited herein is intended to include all sub-ranges subsumed therein. Singular encompasses plural and vice versa.

[368] As used herein, the term "polymer" refers to oligomers and both homopolymers and copolymers, and the prefix "poly" refers to two or more. ‘Including’, ‘for example’ and like terms means including for example but not limited to.

[369] The terms "comprising" and "comprises" as used herein are synonymous with "including" or "containing" and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. Additionally, although the present invention has been described in terms of “comprising”, the processes, materials, and coating compositions detailed herein may also be described as “consisting essentially of’ or “consisting of’.

[370] When used herein, “average” refers to mean average, unless otherwise provide for.

[371] Where ranges are provided in relation to a genus, each range may also apply additionally and independently to any one or more of the listed species of that genus.

[372] All the features contained herein may be combined with any of the above aspects in any combination. [373] For a better understanding of the invention, and to show how aspects of the same may be carried into effect, reference will now be made, by way of example, to the following experimental data and figures.

EXAMPLES

BRIEF DESCRIPTION OF DRAWINGS

[374] Aspects of the present disclosure will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

[375] Figure 1 shows a partially cut-through perspective view of a spiral wound membrane apparatus.

[376] Figure 2 shows a front perspective view of a first embodiment of a feed spacer according to the present invention.

[377] Figure 3 shows a rear perspective view of the first embodiment of a feed spacer according to the present invention.

[378] Figure 4 shows a side view of the feed spacer according to first embodiment of the present invention.

[379] Figure 5 shows a front view of the feed spacer according to the first embodiment of the present invention.

[380] Figure 6 shows an enlarged perspective view of a spacer member of the feed spacer according to the present invention.

[381 ] Figure 7 shows the same enlarged perspective view of a spacer member and flow modifier member, with indication of the various vertical, lateral, and longitudinal planes referred to herein.

[382] Figure 8 shows the same enlarged perspective view of a spacer member and flow modifier member, with indication of the various vertical, lateral, and longitudinal planes referred to herein.

[383] Figure 9 shows a front perspective view of a spacer member of the feed spacer according to a second embodiment of the present invention.

[384] Figure 10 shows a rear perspective view of the feed spacer according to the second embodiment of the present invention.

[385] Figure 11 shows an enlarged perspective view of a spacer member and flow modifier member of the second embodiment of the feed spacer of the present invention, with indication of the various vertical, lateral, and longitudinal planes referred to herein.

[386] Figure 12 shows a front perspective view of a third embodiment of a feed spacer according to the present invention. [387] Figure 13 shows a rear perspective view of a third embodiment of a feed spacer according to the present invention.

[388] Figure 14 shows an enlarged front perspective view of a spacer member and flow modifier member, with indication of the various vertical, lateral, and longitudinal planes referred to herein.

[389] Figure 15 shows a plot comparing the pressure drop of the feed spacer of the present invention compared to other commercially available feed spacers.

[390] Figure 16 shows a plot comparing the permeate flux and pressure drop of the feed spacer of the present invention compared to other commercially available feed spacers.

[391] Figure 17 shows a front perspective view of the first embodiment of a feed spacer according to the present invention, with indication of fluid flow pathways associated therewith.

[392] Figure 18 shows a front perspective view of the first embodiment of a feed spacer according to the present invention, with indication of fluid flow pathways along a vertical slice of the feed spacer extending along the direction of fluid flow.

[393] Figure 19 shows a top view of the first embodiment of a feed spacer according to the present invention, with indication of fluid flow pathways associated therewith.

DESCRIPTION OF EMBODIMENTS

[394] Figure 1 shows a perspective of a partially unravelled spiral wound membrane 10. The spiral wound membrane 10 comprises the feed spacer 12 of the present invention. The spiral wound membrane 10 has a membrane component 14 and a permeate spacer 16. These components are arranged in a layered arrangement as shown. The layered arrangement is spirally arranged to provide a spatially efficient filtration device.

[395] As shown in Figures 2-8, there is provided a feed spacer 100 for a spiral wound membrane 10 according to a first embodiment of the present invention.

[396] The feed spacer 100 is formed of a plurality of spacer members 102 and a plurality of flow modifier members 106. The spacer members 102 are operable to space apart adjacent membrane envelope components 14 of the spiral wound membrane 10.

[397] The feed spacer 100 has an upper membrane-contacting surface 118 and a lower membrane-contacting surface (not shown). The upper and lower membrane-contacting surfaces are operable to contact the membrane component 14 of the spiral wound membrane 10.

[398] The separation between adjacent membrane envelopes 14 provided by the spacer member 102 forms a fluid flow channel 104. The fluid flow channel 104 is operable to allow the passage of fluids, such as water, seawater, and the like. The skilled person will appreciate that various other fluids should be applicable and compatible with the feed spacer 100. The fluid substantially flows in a fluid flow direction 110 under elevated pressure. [399] The feed spacer 100 is arranged in the spiral wound membrane 10, as shown in Figure 1 , with a feed flow input (not shown) along one edge, and a retentate output at an opposing edge that is downstream of the feed flow input.

[400] As shown in Figure 8, each spacer member 102 has a horizontal (lateral-longitudinal) cross-section 102E, as viewed along section E, the periphery of which is delineated by a closed planar curve. As Figures 4 and 6 show, the closed planar curve of the horizontal cross-section 102E has a leading face 112, a trailing face 116, and a pair of opposed (first and second) side faces 114.

[401 ] The closed planar curve horizontal cross-section 102E, as viewed along section E, is bound by faces comprising at least the leading face 112 and the trailing face 1 16, and first and second side faces 1 14.

[402] The leading face 112, trailing face 116, and pair of side faces 114 are formed from a series of sequentially joined arcs. Each of the arcs is defined by a radius of curvature. In other words, the leading face 1 12, trailing face 1 16, and pair of side faces 1 14 of the spacer member 102 are curved. The leading face 112 and trailing face 116 are substantially straight in the vertical direction, as shown by the Z direction in Figure 8.

[403] The leading face 112 is arranged to face toward the upstream direction of the fluid flow so that it is the first surface of the spacer member 102 to contact the fluid flow. The trailing face 116 is arranged to face substantially toward the downstream direction of the fluid flow so that it is the last surface of the spacer member 102 to contact the fluid flow.

[404] As shown in Figures 1 , 2, and 6, the first and second side faces 114 are configured to connect the vertical edges 113 of the leading face 1 12 and the vertical edges 117 of the trailing face 116.

[405] The radius of curvature of the arc defining the periphery of the horizontal cross-section 102E of the leading face 112 is smaller than the radius of curvature of a pair of arcs that define the region of the largest width of the spacer member 102. In other words, the curvature of the arc that defines the leading face 112 is larger than the curvature of the arcs that define the side faces 114.

[406] The radius of curvature of the arc defining the trailing face 116 of the spacer member 102 is smaller than the radius of curvature of the arcs defining the region of the largest width of the spacer member 102. In other words, the curvature of the arc that defines the trailing face 1 16 is larger than the curvature of the arcs that define the side faces 1 14. The width of the leading face 112 of the spacer member 102 is smaller than the largest width of the spacer member 102. The width of the trailing face 116 of the spacer member 102 is smaller than the largest width of the spacer member 102. [407] As shown in Figure 8, X, Y, and Z show the directions of the longitudinal, lateral, and vertical axes of the spacer member, respectively. These directions correspond with the lateral, longitudinal, and vertical axes of the feed spacer.

[408] As Figure 8 further illustrates, the spacer member 102 has a lateral axis in direction Y along its largest width. The spacer member 102 is substantially symmetrical about the lateral axis. In other words, the spacer member 102 is substantially symmetrical about a lateral-vertical crosssection 102F, as viewed along section F, as shown in Figure 8.

[409] The spacer member 102 has a longitudinal axis in direction X along the largest length of the spacer member 102. The spacer member 102 is substantially symmetrical about the longitudinal axis. In other words, the spacer member 102 is substantially symmetrical about a longitudinal-vertical cross-section 102G as viewed along section G, as shown in Figure 8.

[410] The radii of curvature defining the leading face 112 and the trailing face 116 are substantially aligned parallel with the longitudinal axis of the spacer member 102. The longitudinal axis of the spacer member 102 extends in the X direction between the apex of the curved leading face 1 12 and the apex of the curved trailing face 1 16.

[411] The arc defining the curved leading face 112 is convex with respect to the direction of fluid flow 1 10. The arc defining the curved trailing face 1 16 is concave with respect to the direction of the fluid flow 110. The leading face 112 has a radius of curvature of < 0.17 mm. The trailing face 116 has a radius of curvature of < 0.17 mm.

[412] Returning to Figures 2 and 3, the longitudinal axis of the spacer member 102 along direction X is substantially aligned with the direction of fluid flow 1 10.

[413] The side faces 114 are curved laterally outwardly from a midpoint of the longitudinal axis of the spacer member 102. The side faces 114 are curved in a direction that is horizontally perpendicular to the direction of the fluid flow 110. In other words, the side faces 114 are curved in the Y direction of Figure 8, away from the longitudinal-vertical cross-section 102G, as viewed along section G, of the spacer member 102. The radii of curvature defining the curvature of the arcs that define the side faces 114 of the spacer member 102 are aligned substantially perpendicular to the longitudinal axis of the spacer member 102 along direction X.

[414] The first and second side faces 114 of the spacer member 102 have the same radius of curvature. The first and second side faces 114 of the spacer member 102 have a radius of curvature of < 2.4 mm.

[415] Figure 8 shows the spacer member 102 with the associated largest length, width, and height measurement which correspond with directions X, Y, and Z, respectively. The length and width dimensions of the spacer member 102 substantially align with the lateral and longitudinal axes of the spacer member 102. The longitudinal axis of the spacer member 102, as shown by direction X of Figure 8, is substantially aligned parallel with respect to the direction of fluid flow 110. The radii of curvature of the leading face 112 and trailing face 116 of the spacer member 102 are substantially aligned parallel with respect to the direction of fluid flow 110.

[416] The spacer member 102 has a height of < 1 .2 pm, a width of < 1 mm, and a length of < 2.6 mm.

[417] Each flow modifier member 106 has a leading face 124. The leading face 124 of the flow modifier member 106 is arranged to face toward the upstream direction of the fluid flow 110 so that it is the first surface of the flow modifier member 106 to contact the fluid flow.

[418] The flow modifier member 106 has trailing face 126. The trailing face 126 of the flow modifier member 106 is arranged to face toward the downstream direction of the fluid flow 110 so that it is the last surface of the flow modifier member 106 to contact the fluid flow.

[419] As shown in Figure 7, X, Y, and Z show the directions of the longitudinal, lateral, and vertical axes of the flow modifier member, respectively.

[420] The leading face 124 of the flow modifier member 106 is closer to a feed inflow inlet of the spiral wound membrane than the trailing face 126 of the flow modifier member 106. The trailing face 126 of the flow modifier member 106 is closer to a retentate flow outlet of the spiral wound membrane than the leading face 124 of the flow modifier member 106.

[421] As Figure 7 shows, the flow modifier member 106 has a lateral-vertical cross-section 106D, as viewed along section D, wherein the width of the flow modifier member 106 is larger than the largest height of the flow modifier member 106.

[422] The flow modifier member 106 has a largest width in the Y direction of < 1.4 mm and a largest height in the Z direction of < 0.26 mm. The flow modifier member has a a largest length in the X direction of < 4 mm. As Figure 7 illustrates, the flow modifier member 106 has a substantially wedge-shaped lateral-vertical cross-section 106A.

[423] The leading face 124 of the flow modifier member 106 is curved in the downstream direction. In other words, the leading face 124 is curved away from the incoming fluid flow. As such, the leading face 124 has a convex curvature relative to the direction of the fluid flow 1 10.

[424] The curved leading face 124 of the flow modifier member 106 is formed of an arc. The radius of curvature of the curved leading face 124 is substantially aligned parallel with the direction of fluid flow 110. The radius of curvature of the leading face 124 is substantially aligned parallel with the of the lateral axis of the flow modifier member 106 in the Y direction of Figure 7 or in the X direction of Figure 8. The curved leading face has a radius of curvature of < 0.1 mm.

[425] The trailing face 126 of the flow modifier member 106 is substantially planar. The substantially planar trailing face 126 is substantially vertically orthogonal to a longitudinal-lateral (horizontal) plane 106C, as viewed along section C, of the flow modifier member 106. The substantially planar trailing face 126 is substantially parallel to the longitudinal-vertical plane 106 A and/or 106B, as viewed along sections A and/or B, respectively, of the flow modifier member 106.

[426] The flow modifier member 106 further has an upper face 128. The upper face 128 of the flow modifier member 106 extends between an upper end of the leading face 132 and an upper end of the trailing face 134. The upper face 128 of the flow modifier member 106 faces substantially toward the upper membrane component 14 of the spiral wound membrane 10.

[427] The flow modifier member 106 further has a lower face 130. The lower face 130 of the flow modifier member 106 extends between a lower end of the leading face 136 and a lower end of the trailing face 138.

[428] The upper face 128 faces substantially toward the upper component of the adjacent component of the spiral wound membrane. The lower face 130 faces substantially toward the lower component of the adjacent component of the spiral wound membrane.

[429] The upper face 128 of the flow modifier member 106 is angled relative to a horizontal plane Y, as shown in Figures 4 and 5. The upper face 128 of the flow modifier member 106 is curved towards the downstream direction. The upper face 128 is angled < 10° relative to the horizontal plane Y.

[430] The lower face 130 of the flow modifier member 106 is angled relative to a horizontal plane Y, as shown in Figures 4 and 5. The lower face 130 of the flow modifier member 106 is curved towards the downstream direction. The lower face 130 is angled < 10° relative to the horizontal plane.

[431] The horizontal plane Y, shown in Figures 4 and 5, is a plane which encompasses the lateral-longitudinal plane 106C of the flow modifier member 106, as viewed along section C, as shown in Figure 7. The normal vectors to the horizontal plane Y are arranged to extend vertically in the Z direction of Figures 7 and 8, substantially toward the membrane envelopes 14 of the spiral wound membrane 10 on either side of the feed spacer 100.

[432] Each flow modifier member 106 has a longitudinal axis that extends in the X direction, as shown in Figure 7, that extends along its length. The longitudinal axis of the flow modifier member 106 substantially aligned parallel with the vertical-longitudinal axis 106A/106B of the flow modifier member 106.

[433] Referring back to Figure 2, the plurality of flow modifier members 106 includes a flow modifier member portion 108. The flow modifier member portion 108 extends between a pair of adjacent spacer members 102. The flow modifier member portion 108 has a length of < 4 mm.

[434] The spacer member 102 comprises an upper portion that projects above the flow modifier member 106, and a lower portion that projects below the flow modifier member 106. The upper portion is operable to space a membrane component from an upper face 128 of the flow modifier member 106. Similarly, the lower portion is operable to space a membrane component from a lower face 130 of the flow modifier member 106.

[435] The upper and lower portions of the spacer member 102 are substantially vertically and concentrically aligned. The upper and lower membrane-contacting faces of the spacer member 102 are substantially vertically and concentrically aligned.

[436] The upper and lower portions of the spacer member have a height of < 0.29 mm. The difference between the height of the upper and lower projecting portions of the spacer member is < 0.1 mm.

[437] The plurality of flow modifier members 106 includes > 10 flow modifier members 106.

[438] As shown in Figure 6, the flow modifier member 106 is attached to the spacer member 102. The flow modifier member 106 is attached to the spacer member 102 at a midpoint along the height of the spacer member 102.

[439] As shown in Figures 2, the plurality of flow modifier members 106 are grouped into a first series of flow modifier members 144a,b,c and a second series of flow modifier members 146a,b,c.

[440] The first series of flow modifier members 144a,b,c has a plurality of flow modifier members that are spaced apart and substantially aligned in parallel. The second series of flow modifier members 146a, b,c has a plurality of flow modifier members that spaced apart and substantially aligned in parallel.

[441] The flow modifier members 106 of the first series 144a,b,c are relatively more aligned with each other than with the flow modifier members of the second series 146a,b,c. The flow modifier members 106 of the second series 146a,b,c are relatively more aligned with each other than with the flow modifier members 106 of the first series 144a,b,c.

[442] Adjacent flow modifier members from the same series are spaced < 5 mm apart. In other words, each flow modifier member from the first series is spaced < 5 mm away from adjacent flow modifier members within the first series, each flow modifier member from the second series is spaced < 5 mm away from adjacent flow modifier members within the second series.

[443] The flow modifier members 106 in the first series 144a,b,c have a shared longitudinal axis that extends along the length of the collective orientation of the first series 144a,b,c. flow modifier members 106 in the second series 146a,b,c have a shared longitudinal axis that extends along the length of the collective orientation of the second series 146a,b,c.

[444] The first series of flow modifier members 144a,b,c are arranged to intersect with the second series of flow modifier members 146a,b,c substantially so that each flow modifier member 106 of the first series intersects with each flow modifier member 106 of the second series.

[445] The longitudinal axes of the first series of flow modifier members 144a, b,c is angularly offset by < 80° to the longitudinal axes of the second series of flow modifier members 146a,b,c. [446] The longitudinal axes of both the first and second series of flow modifier members 144a,b,c, 146a,b,c are angularly offset by < 40° relative to the direction of fluid flow 110.

[447] As Figures 4 and 5 show, the plurality of flow modifier members 140 in the first and second series of flow modifier members 144a,b,c, 146a, b, c are arranged in a single horizontal plane. The horizontal plane Y extends through the lateral-longitudinal (horizontal) plane/cross-section 106C of the flow modifier member 106 and lateral-longitudinal (horizontal) plane/cross-section 102E of the spacer member 102.

[448] A spacer member 102 is located at each intersection between the flow modifier members of the first series 144a,b,c and the second series 146a,b,c. The spacer member 102 is integrally formed with the intersecting flow modifier members 106 of the first and second series 144a,b,c, 146a,b,c by additive manufacturing.

[449] The flow modifier member 106 has a lateral-vertical cross-section 106D, as viewed along section D, wherein the height of the leading face 124 is smaller than the largest height of the lateral-vertical cross-section 106D. The trailing face 126 defines the largest height of the lateralvertical cross-section 106D.

[450] The flow modifier member has a lateral-vertical cross-section 106D, as viewed along section D, whereby the width of the lateral-vertical cross-section 106D is larger than the height of the lateral-vertical cross-section 106D.

[451] The lateral-vertical cross-section 106D of the flow modifier member 106 has a largest height of < 0.26 mm.

[452] The lateral-vertical cross-section 106D of the flow modifier member 106 has a lateral axis, along direction Y of Figure 7, that extends along the largest width of the lateral-vertical crosssection 106D, as viewed along section D. The lateral-vertical cross-section 106D is substantially symmetrical about the lateral axis of the flow modifier member i.e., along the Y direction of Figure 7. The lateral axis of the flow modifier member 106 extends in the Y direction of Figure 7, between an apex of the leading face 124 and a vertical midpoint of the trailing face 126.

[453] The lateral-vertical cross-section 106D of the flow modifier member 106 has a largest width of < 1.4 mm.

[454] The flow modifier member 106 has a plurality of flow modifier member portions 107 which extends between adjacent spacer members 102 wherein > 85% of the flow modifier member portions 107 have the lateral-vertical cross-section 106D.

[455] The flow modifier member 107, or portion 107 thereof, has an average largest height of < 0.26 mm. The average height is a mean average height of the lateral-vertical cross-section 106D, as viewed along section D. [456] The average height of the leading face 124 of the flow modifier member 106, or a portion 107 thereof is < 0.175 mm.

[457] The average height of the leading face 124 of the flow modifier member 106, or a portion 107 thereof is < 30% of the height of the spacer member 102.

[458] The average height of the trailing face 126 of the flow modifier member, or a portion 107 thereof, is < 0.26 mm.

[459] The average height of the trailing face 126 of the flow modifier member 106, or a portion 107 thereof is < 32.5% of the height of the spacer member 102.

[460] As evident from Figures 4-8, the height of the spacer member 102 is larger than the height of the flow modifier member 106. The flow modifier members 106 intersect with the spacer member 102 at a midpoint of the spacer member 102, thereby providing the spacing above and below the flow modifier member for fluid flow.

[461] Figures 9-11 show a second embodiment of the feed spacer 200 according to the present invention. The second embodiment of the feed spacer 200 is identical to the first embodiment 100 except that the flow modifier member 206 has a lateral-vertical cross-section 206C, as viewed along section C, comprising a projection that substantially extends in the vertical, Z as shown in Figure 11 , direction. The projection, or bulged portion 252, is operable to increase the lateral and vertical turbulence and/or tortuosity of the fluid flow.

[462] The bulged portion 252, comprises an outwardly extending, or convex, curvature in the upper and lower faces 228, 230 of the flow modifier member 206.

The bulged portion is arranged proximate to the middle of the flow modifier member portion 207 in the longitudinal direction, shown by the X direction in Figure 11 , relative to the ends of the flow modifier member portion 207. In other words, the bulged portion 252 is substantially centrally disposed along the length of the flow modifier member portion 207 between adjacent spacer members 202.

[463] The bulged portion 252 is laterally arranged to be closer to the trailing face 226 of the flow modifier member than the leading face 224 of the flow modifier member 206.

[464] As Figure 11 shows, the flow modifier member 206, or a portion 207 thereof, comprises a longitudinal-vertical cross-section 206B, as viewed along section A, wherein the largest height of the longitudinal-vertical cross-section is > 30% along the length of the longitudinal-vertical crosssection 206B from an adjacent intersection between flow modifier members 206. The largest height of the longitudinal-vertical cross-section 206B is < 70% along the length of the longitudinalvertical cross-section 206B from an adjacent intersection between flow modifier members 206.

[465] The flow modifier member 206, or a portion 207 thereof, comprises a series of lateralvertical cross-sections 206C, 206D in an X-Y-Z sequence along its length in the longitudinal direction, as shown by direction X in Figure 11. The lateral-vertical cross-section 206C has a larger height than the lateral-vertical cross-sections 206D of X or Z.

[466] The series of X, Y, and Z cross-sections are substantially evenly spatially separated along the longitudinal-vertical cross-section 206A, 206B of the flow modifier member 206, or a portion 207 thereof. The X and Z cross-sections are more proximate to the adjacent spacer members 202 or intersections than cross-section Y. In other words, cross-section Y is more centrally disposed along the length of the flow modifier member 206, or portion thereof, than cross-sections X and/or Z.

[467] The bulged portion 252 is not operable to contact the upper or lower membrane components 14 when in use. Rather, the bulged portion 252 has a height that is larger than the average height of the flow modifier member 206, or portion 207, thereof but not larger than the height of the spacer member 202.

[468] The largest height of the bulged portion 252 is < 150% larger than the average height of the flow modifier member 206, or portion 207 thereof.

[469] The largest height of the bulged portion 252 is < 230% larger than the smallest height of the flow modifier member 206, or portion 207 thereof.

[470] The largest height of the bulged portion 252 is < 44% smaller than the height of the spacer member 202.

[471] The flow modifier member 206, or a portion 207 thereof, comprises a first lateral-vertical cross-section 206D, as viewed along section D, and a second lateral-vertical cross-section 206C, as viewed along section C. The second lateral-vertical cross-section 206C has a larger average height than the first lateral-vertical cross-section 206D.

[472] The second lateral-vertical cross-section 206C has a largest height that is < 250% of the height of the first lateral-vertical cross-section 206D.

[473] The second lateral-vertical cross-section 206C has an largest height of < 0.55 mm.

[474] The first lateral-vertical cross-section 206D has an largest height of < 0.26 mm.

[475] The flow modifier member 206, or portion 207 thereof, has < 90% to > 30% of the first lateral-vertical cross-section 206D.

[476] The flow modifier member 206, or portion 207 thereof, has < 20% to > 17% of the second lateral-vertical cross-section 206C.

[477] The flow modifier member 206, or portion 207 thereof, has a first longitudinal-vertical crosssection 206A and a second longitudinal-vertical cross-section 206B. The second longitudinal vertical cross-section 206B has a larger height than the first longitudinal-vertical cross-section 206A. [478] The first longitudinal-vertical cross-section 206A is operable to be closer to the leading face 224 of the flow modifier member 206, or portion 207 thereof, than the second longitudinal-vertical cross-section 206B of the flow modifier member 206, or portion 207 thereof.

[479] The trailing face 226 of the flow modifier member 206, or portion 207 thereof, has the second longitudinal-vertical cross-section 206B.

[480] The first longitudinal-vertical cross-section 206A has a height that is substantially the same or constant along its length. In other words, the first longitudinal-vertical cross-section has a height that deviates from a mean average of the height of the flow modifier member 206, or portion 207 thereof, by a small amount. The first longitudinal-vertical cross-section 206A has a height that deviates from the mean average height of the flow modifier member 206, or portion 207 thereof by < 5%.

[481] Figures 12-14 show a third embodiment of the feed spacer 300 according to the present invention. The third embodiment of the feed spacer 300 is identical to the first embodiment of the feed spacer 100 except that the spacer member 302 has a substantially wedge-shaped longitudinal-lateral (horizontal) cross-section 302E, as viewed along section E as shown in Figure 14.

[482] The leading face 312 and first and second side faces 314 are formed of a series of sequentially joined arcs. Each of the arcs is defined by a radius of curvature. In other words, the leading face 312 and first and second side faces 314 of the spacer member 302 are curved.

[483] The leading face 312 is arranged to face toward the upstream direction of the fluid flow so that it is the first surface of the spacer member 302 to contact the fluid flow. The trailing face 116 is arranged to face substantially toward the downstream direction of the fluid flow so that it is the last surface of the spacer member 102 to contact the fluid flow.

[484] The first and second side faces 314 are arranged to connect the edges of the leading face 312 and the edges of the trailing face 316.

[485] The radius of curvature of the arc defining the leading face 214 of the spacer member 302 is smaller than the curvature of the arcs defining the region of the largest width of the spacer member 302. In other words, the curvature of the arc that defines the leading face 314 is larger than the arcs that define the side faces 314.

[486] The leading face 312 of the spacer member 302 is curved in the downstream direction. In other words, the leading face 312 is curved away from the incoming fluid flow. As such, the leading face 312 has a convex curvature relative to the direction of the fluid flow 310.

[487] The radius of curvature of the curved leading face 312 is substantially aligned parallel with the direction of fluid flow 310. The radius of curvature of the leading face 312 is substantially aligned parallel with the of the longitudinal axis of the spacer member 302, in the X direction as shown in Figure 14. [488] The curved leading face has a radius of curvature of < 4 mm. The curved first and second faces 314 have a radius of curvature of < 4 mm.

[489] The trailing face 316 of wedge-shaped spacer member 302 is not curved. In other words, the trailing face 316 of the spacer member 302 is substantially planar. The substantially planar trailing face 316 is substantially vertically orthogonal to a longitudinal-lateral (horizontal) crosssection 302E, as viewed along section E, of the spacer member 302. The substantially planar trailing face 316 is substantially parallel to the longitudinal-vertical cross-section 302G, as viewed along section G, of the spacer member 302.

[490] As shown in Figure 14, the wedge-shaped spacer member 302 has a longitudinal axis extending in the X direction. The longitudinal axis extends along the largest length of the spacer member 302. The spacer member 302 is substantially symmetrical about the longitudinal axis. The longitudinal axis of the spacer member 302 extends between an apex of the curved leading face 312 and a middle of the planar trailing face 316.

[491] The longitudinal axis of the wedge-shaped spacer member 302 is operable to be substantially aligned parallel with the direction of the fluid flow 310.

[492] The leading face 312 of the wedge-shaped spacer member 302 has a width that is smaller than the largest width of the spacer member 302.

[493] The trailing face 316 is wider than the leading face 312 of the spacer member 302. The trailing face has the largest width of the spacer member 302.

[494] The wedge-shaped spacer member 302 has a largest width of > 3 mm.

[495] The first and second side walls 314 of the wedge-shaped spacer member 302 have a tapered width along the length of the spacer member 302 between the leading face 312 and the trailing face 314. In other words, the first and second side walls 314 have a minimum separation distance proximate to the leading face 312, and a maximum separation distance proximate the trailing face 316.

[496] The wedge-shaped spacer member 302 has a largest length of > 3 mm.

[497] Figures 17-19 show the fluid flow pathways associated with the feed spacers described herein.

EXPERIMENTAL DATA

[498] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the following experimental data. The experimental data referred to herein is shown in Figures 15 and 16.

[499] The feed spacer of the embodiments discussed above is fabricated using an additive manufacturing technique. [500] Feed spacer E1 , E2 and E3 was fabricated using a Formlabs ® Form 3L printer using stereolithography (SLA) which belongs to a family of additive manufacturing methods known as vat photopolymerization. A Rigid 4000 resin was used, this is a glass-filled photopolymer resin. The feed spacer was fabricated in layers, each layer was 50 pm in height.

[501] The manufacture of feed spacers E1 , E2 and E3 were fabricated using the steps below.

[502] First, the printer was primed and the feed spacers were printed. Once printed, support materials were removed, and the resulting feed spacer was washed in isopropyl alcohol (IPA) for 15 minutes to remove any remaining residue of the liquid resin. Excess IPA was subsequently wiped off.

[503] The printed feed spacers were then UV-cured at a temperature of 80°C for 15 minutes. The cured feed spacers were then washed with water to prepare them for testing.

[504] The feed spacer of the embodiments discussed above were tested against commercially available feed spacers.

[505] An Alfa Laval ® M20 cross-flow system was used to test the feed spacers. A nanofiltration membrane was used in conjunction with a range of 3D-printed feed spacers which were produced using SLA techniques. Experiments were performed at a trans membrane pressure (TMP) of 25 bar, a feed flow rate of 6L/min. All experiments were conducted at room temperature. The feed fluid comprised 20,000 ppm NaCI, and 20,000 ppm MgSC in water.

[506] The various 3D-printed feed spacers were tested using the steps below.

[507] 160 g of NaCI was mixed with 328 g of MgSG -TF in 8 L of water to produce a feed fluid containing 20,000 ppm NaCI and 20,000 ppm MgSC . The prepared feed fluid was poured into the feed tank of the M20 system.

[508] The feed spacer for testing was installed in a Sterlitech Sepa CF cell, along with an NF membrane and permeate spacer. The cell was assembled in a cell holder. The pressure was increased using a hydraulic pump up to a pressure of 70 bar.

[509] A pressure control valve was opened, at the same time, a pump was switched on and set to a rotational speed of 6 L/min. The pressure control valve was gradually closed to increase the pressure of the system. The rotation speed of the pump was then adjusted until a trans membrane pressure of 25 bar was achieved. The pressure drop across the membrane was measured as a difference between the feed pressure and the retentate pressure.

Measurements were taken for pressure drop (DP) and permeate flux until the system equilibrated and the permeate flux stabilised and the value of equilibrium flux was recorded. Flux is defined as the permeate flow rate per unit area of the membrane:

Wherein, J is the permeate flux in Lm^-2hr¹ (or LMH), Q_P is the permeate flow rate, and A is the area of the membrane.

[510] Finally, the system was flushed with water to clean the internal components. The pump was switched off, the tank was drained, and the membrane and spacers were removed from the cell.

[511] Experimental results were obtained for a range of commercially available biplanar feed spacers (C1-C6) and three variations of the first embodiment (E1-E3) of the feed spacer of the present invention comprising different dimensions, as shown in Table 1 below.

Table 1 - Comparison of thicknesses and associated pressures drop of commercial feed spacers and those according to the present invention.

[512] As the results of Table 1 shows, the feed spacer of the present invention (E1-E3) provide a reduced pressure drop than comparative feed spacers (C1-6) which do not have a flow modifier member. Further, the successive iterations of the 3D-printed spacer of the present invention, where the thickness of flow modifier member was reduced, the pressure drop of the fluid was further reduced, without significant impact on the flux.

[513] The data of Table 1 is summarised in Figure 15 and 16 which show the significance of the improved pressure drop and excess pressure drop compared to the flux of the systems tested.

[514] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. [515] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[516] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[517] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1 . A feed spacer for a spiral wound membrane, such as for water filtration, comprising: a. a spacer member operable to space apart adjacent components of the spiral wound membrane to form a fluid flow channel; and b. a flow modifier member operable to direct fluid flow toward a membrane component of the spiral wound membrane in the fluid flow channel, wherein the spacer member is operable to space the membrane component from the flow modifier member so as to form a fluid flow channel above and below the flow modifier member.

2. The feed spacer of claim 1 , wherein the spacer member comprises a substantially ovalshaped horizontal cross-section.

3. The feed spacer of claims 1 or 2, wherein the flow modifier member comprises a substantially wedge-shaped lateral-vertical cross-section.

4. The feed spacer of claim any preceding claim, wherein the spacer member comprises: a. a leading face, operable to face substantially toward the upstream direction of fluid flow; and b. a trailing face operable to face substantially toward the downstream direction of fluid flow wherein the height of the leading face is smaller than the largest height of the crosssection, wherein the largest height of the cross-section may be toward the trailing face of the cross-section.

5. The feed spacer of any preceding claim, wherein the leading face of the spacer member is curved.

6. The feed spacer of any preceding claim, wherein the curved leading face of the spacer member is curved away from the incoming fluid flow.

SUBSTITUTE SHEET (RULE 26)

7. The feed spacer of any preceding claim, wherein the curved leading face is defined by an arc with a radius of curvature that is substantially aligned parallel with the direction of the fluid flow.

8. The feed spacer of any preceding claim, wherein arc defining the curved leading face has a radius of curvature of < 0.3 mm, such as < 0.25 mm, such as < 0.17 mm.

9. The feed spacer of any preceding claim wherein the trailing face of the spacer member is curved.

10. The feed spacer of any preceding claim wherein the curved trailing face of the spacer member is curved toward from the incoming fluid flow.

11 . The feed spacer of any preceding claim, wherein the curved trailing face is defined by an arc with a radius of curvature that is substantially aligned parallel with the direction of the fluid flow.

12. The feed spacer of any preceding claim, wherein arc defining the curved leading face has a radius of curvature of < 0.3 mm, such as < 0.25 mm, such as < 0.17 mm.

13. The feed spacer of any preceding claim, wherein the leading face of the spacer member comprises a width that is smaller than the largest width of the spacer member.

14. The feed spacer of any preceding claim, wherein the trailing face of the spacer member comprises a width that is smaller than the largest width of the spacer member.

15. The feed spacer of any preceding claim, wherein the trailing face of the spacer member that is substantially planar.

16. The feed spacer of any preceding claim, wherein the trailing face of the spacer member comprises the largest width of the spacer member.

SUBSTITUTE SHEET (RULE 26)

17. The feed spacer of any preceding claim, wherein the spacer member has a horizontal cross-section that is substantially wedge-shaped.

18. The feed spacer of any preceding claim, wherein the spacer member comprises substantially opposed first and second side faces.

19. The feed spacer of any preceding claim, wherein the first and second side faces of the spacer member are curved in a direction that substantially horizontally perpendicular to the direction of the fluid flow.

20. The feed spacer of any preceding claim, wherein the curved first and second side faces of the spacer member have a radii of curvature from < 6 mm, such as < 3 mm, or 2.4 mm.

21 . The feed spacer of any preceding claim, wherein the radius of curvature of the leading face is smaller than the radius of curvature of the first and/or second side face.

22. The feed spacer of any preceding claim, wherein, the curved trailing face has a radius of curvature that is smaller than the radii of curvature of the first and/or second side face.

23. The feed spacer of any preceding claim, wherein the spacer member comprises a lateral axis along its largest width.

24. The feed spacer of any preceding claim, wherein the spacer member is substantially symmetrical about the lateral axis.

25. The feed spacer of any preceding claim, wherein the spacer member comprises a longitudinal axis along its largest length.

26. The feed spacer of claim 25, wherein the spacer member is substantially symmetrical about the longitudinal axis.

SUBSTITUTE SHEET (RULE 26)

27. The feed spacer of any preceding claim, wherein the spacer longitudinal axis is operable to be substantially aligned parallel with the direction of the fluid flow.

28. The feed spacer of any preceding claim, wherein the largest width of the spacer member is from < 2 mm, such as < 1 .5 mm, or < 1 mm.

29. The feed spacer of any preceding claim, wherein the largest length of the spacer member is from < 4 mm, such as < 3.5 mm, or < 2.6 mm.

30. The feed spacer of any preceding claim, wherein the largest height of the spacer member is from < 2.2 mm, such as < 1 .8 mm, or < 1 .2 mm.

31 . The feed spacer of any preceding claim, wherein the height of the spacer member is larger than the height of the flow modifier member.

32. The feed spacer of any preceding claim, wherein the spacer member comprises an upper portion and a lower portion, wherein the upper and/or lower portions are operable to space a membrane component from the flow modifier member.

33. The feed spacer of any preceding claim, wherein the height of the upper and/or lower projection portions of the spacer member that project above and/or below the flow modifier member are from < 0.31 mm, such as < 0.30 mm, or < 0.29 mm.

34. The feed spacer of claim any preceding claim, wherein the flow modifier member comprises: a. a leading face, operable to be the first face of the flow modifier member that contacts the fluid flow; and b. a trailing face, operable to be the last face of the flow modifier member that contacts the fluid flow; wherein the leading face is operable to face relatively upstream compared to the trailing face and the trailing face is operable to face relatively downstream compared to the leading face.

SUBSTITUTE SHEET (RULE 26)

35. The feed spacer of any preceding claim, wherein the leading face of the flow modifier member is curved.

36. The feed spacer of any preceding claim, wherein the curved leading face of the flow modifier member is curved away from the incoming fluid flow.

37. The feed spacer of any preceding claim, wherein the curved leading face has a radius of curvature from < 0.3 mm, such as < 0.12 mm, or < 0.1 mm.

38. The feed spacer of any preceding claim, wherein the leading face of the flow modifier member is substantially horizontally straight.

39. The feed spacer of any preceding claim, wherein the trailing face of the flow modifier member is operable to promote deflection from the flow modifier member toward the adjacent component of the spiral wound membrane.

40. The feed spacer of any preceding claim, wherein the trailing face of the flow modifier member is substantially planar.

41 . The feed spacer of any preceding claim, wherein the substantially planartrailing face of the flow modifier member is substantially vertically orthogonal to a horizontal cross-section of the flow modifier member.

42. The feed spacer of any preceding claim, wherein the flow modifier member comprises a variable height along a lateral-vertical cross-section of the flow modifier member.

43. The feed spacer of any preceding claim, wherein the height of the leading face is smaller than the height of the trailing face.

44. The feed spacer of any preceding claim, wherein the flow modifier member may have a largest height from < 0.65 mm, such as < 0.4 mm, or < 0.26 mm.

SUBSTITUTE SHEET (RULE 26)

45. The feed spacer of any preceding claim, wherein the flow modifier member comprises a lateral axis, extending across the largest width of the lateral-vertical cross-section.

46. The feed spacer of any preceding claim, wherein the flow modifier member is substantially symmetrical about the lateral axis.

47. The feed spacer of any preceding claim, wherein a lateral-vertical cross section of the flow modifier member has a largest width from < 2.4 mm, such as < 2.1 mm, or < 1 .4 mm.

48. The feed spacer of any preceding claim, wherein the flow modifier member further comprises: a. an upper face, extending between an upper end of the leading face and an upper end of the trailing face; and b. a lower face, extending between a lower end of the leading face and a lower end of the trailing face.

49. The feed spacer of any preceding claim, wherein the upper and lower faces are substantially planar.

50. The feed spacer of any preceding claim, wherein the upper face is operable to face substantially toward an upper component of the adjacent components.

51. The feed spacer of any preceding claim, wherein the lower face is operable to face substantially toward a lower component of the adjacent components.

52. The feed spacer of any preceding claim, wherein the upper and/or lower faces of the flow modifier member are angled relative to a lateral axis of the feed spacer.

53. The feed spacer of any preceding claim, wherein the upper and/or lower faces of the flow modifier member are angled from < 30°, such as < 15°, or < 10° from the lateral axis of the flow modifier member.

SUBSTITUTE SHEET (RULE 26)

54. The feed spacer of any preceding claim, further comprising a flow modifier member portion that extends between adjacent spacer members and/or intersection points.

55. The feed spacer of any preceding claim, wherein the flow modifier member portion has a length extending between adjacent spacer members and/or intersection points from < 6.5 mm, such as < 5 mm, or < 4 mm.

56. The feed spacer of any preceding claim, wherein the flow modifier member comprises a bulged portion that is operable to increase the lateral and vertical turbulence of the fluid flow compared to a non-bulged part of the flow modifier member.

57. The feed spacer of any preceding claim, wherein the bulged portion comprises a substantially vertically extending projection.

58. The feed spacer of any preceding claim, wherein the vertically extending projection extends from the upper and/or lower faces of the flow modifier member.

59. The feed spacer of any preceding claim, wherein the bulged portion is arranged proximate to a midpoint in a longitudinal direction of a flow modifier member portion extending between adjacent spacer members.

60. The feed spacer of any preceding claim, wherein the bulged portion comprises a height that is larger than the average height of the flow modifier member portion.

61 . The feed spacer of any preceding claim, wherein the spacer member is not operable to contact the membrane component, when in use.

62. The feed spacer any preceding claim, comprising a plurality of flow modifier members, such as > 10, such as > 50, or > 100 flow modifier members.

63. The feed spacer of any preceding claim, wherein the longitudinal axes of the plurality of flow modifier members are aligned substantially parallel.

SUBSTITUTE SHEET (RULE 26)

64. The feed spacer of any preceding claim, wherein the longitudinal axes of the flow modifier members are arranged to intersect with each other.

65. The feed spacer of any preceding claim, wherein the longitudinal axes of the intersecting flow modifier members are angularly offset relative to each other by an angle from < 130°, such as < 100°, or < 80°.

66. The feed spacer of any preceding claim, wherein a flow modifier member is intersected by a plurality of flow modifier members at spaced intervals.

67. The feed spacer of any preceding claim, comprising a first series and a second series of flow modifier members, each comprising a plurality of flow modifier members.

68. The feed spacer any of any preceding claim, wherein the first series of flow modifiers members comprises a plurality of at least partially spaced and substantially parallelly aligned flow modifier members, and the second series of flow modifier members comprises a plurality of at least partially spaced and substantially parallelly aligned flow modifier members

69. The feed spacer of any preceding claim, wherein the flow modifier members of the first and/or second series are spatially separated from each other in a lateral direction relative to the feed spacer, wherein the spatial separation between the adjacent flow modifier members creates a fluid flow channels through which the fluid may flow.

70. The feed spacer of any preceding claim, wherein the flow modifier members of the first and/or second series of flow modifier members are laterally separated from each other by a distance from < 7 mm, such as < 6 mm, or < 5 mm.

71. The feed spacer of any preceding claim, wherein the flow modifier members of the first series comprise a shared longitudinal axis that extends along the length of the collective orientation of the series, and the flow modifier members of the second series comprise a shared longitudinal axis that extends along the length of the collective orientation of the series.

SUBSTITUTE SHEET (RULE 26)

72. The feed spacer of any preceding claim, wherein the shared longitudinal axes of the first and/or second series of flow modifier member are operable to be angularly offset to direction of the fluid flow.

73. The feed spacer of any preceding claim, wherein the shared longitudinal axis of the first and/or second series are angularly offset to the direction of the fluid flow by an angle from < 65°, such as < 50°, or 40°.

74. The feed spacer of any preceding claim, wherein the shared longitudinal axes of the second series of flow modifier members are angularly offset relative to the shared longitudinal axes of the first series of flow modifier members.

75. The feed spacer of any preceding claim wherein the shared longitudinal axis of the first and second series of flow modifier members are angularly offset relative to each other by an angle from < 130°, such as < 100°, or < 80°.

76. The feed spacer any preceding claim, comprising a plurality of spacer members, such as > 10, such as > 50, or > 100 spacer members.

77. The feed spacer of any preceding claim, wherein a spacer member is located at an intersection between flow modifier members.

78. The feed spacer of any preceding claim, wherein a spacer member is located at > 70%, such as > 80%, or > 90% of intersections between flow modifier members.

79. The feed spacer of any preceding claim, wherein the average distance between laterally adjacent spacer members is from < 7 mm, such as < 6 mm, or < 5 mm.

80. The feed spacer of any preceding claim, wherein the average distance between longitudinally adjacent spacer members is from < 7 mm, such as < 6 mm, or < 5 mm.

81 . The feed spacer of any preceding claim, wherein the average spatial density of spacer members across the feed spacer is from < 36 cm^-2, such as < 20 cm^-2, or < 10 cm^-2.

SUBSTITUTE SHEET (RULE 26)

82. The feed spacer of any preceding claim, wherein the spacer member is attached to the respective flow modifier member intersection point.

83. The feed spacer of any preceding claim, wherein the spacer member is integrally formed with the respective intersection point.

84. The feed spacer of any preceding claim, wherein the flow modifier member projects from a side face of a spacer member.

85. The feed spacer of any preceding claim, wherein a longitudinal axis of the flow modifier member is angularly off set to a longitudinal axis of the spacer member.

86. The feed spacer of any preceding claim, wherein the longitudinal axis of the flow modifier member is angularly off set to the longitudinal axis of the spacer member by off-set at an angle of

< 65°, such as < 50°, or < 40°.

87. The feed spacer of any preceding claim, wherein the intersecting flow modifier members are in substantially the same horizontal plane.

88. The feed spacer of any preceding claim, wherein > 50%, such as > 75%, or > 90% of the flow modifier members are in substantially the same horizontal plane.

89. A method of preparing the feed spacer according to any preceding claim, by additive manufacturing, such as inkjet printing, such as material jetting 3D printing.

SUBSTITUTE SHEET (RULE 26)

90. A method of preparing the feed spacer according to any preceding claim, comprising the steps of: a. producing a feed spacer component, optionally comprising a support material, by additive manufacturing; b. removing the optional support material by dissolving the support material with a solvent, or by mechanically removing the support material; c. optionally UV-curing the feed spacer component.

91 . The method of claim 89 or 90, wherein the feed spacer component is fabricated using a glass-filled photopolymer resin, such as Rigid 4000 resin.

92. The method of claim 89-91 , wherein the feed spacer component is fabricated in layers, wherein each layer is 50 pm in height.

93. The method of any of claims 89-92, wherein the fabricated feed spacer component is washed with a polar solvent or non-polar solvent, such as isopropyl alcohol.

94. The method of any of claims 89-93, wherein the fabricated component is UV cured at a temperature of at least 80 °C, optionally for at least 15 minutes.

95. The method of any of claims 89-94, wherein the additive manufacturing technique is selected from any 3D printing technology, such as material jetting 3D printing, digital light processing, two-photon polymerisation, two colour photo-polymerisation, inkjet printing, binder jet printing, stereolithography (SLA), direct ink writing, three-dimensional printing, selective laser sintering, selective laser melting, laminated object manufacturing, or fused deposition modelling; preferably inkjet printing or material jetting 3D printing.

96. A spiral wound membrane comprising a feed spacer according to any of claims 1 -88.

97. A water treatment module comprising a feed spacer according to any of claim 1-88, or a spiral wound membrane according to claim 96.

SUBSTITUTE SHEET (RULE 26)